I am glad to assist you in this endeavour of enlightenment.

Also, just because you have credentials in a field doesn't mean you are correct either. Nor does it override my own credentials.

I'm not saying it does, you just come across as a prick with the way you assert yourself, specifically with the "Now you can feel a little more educated on the topic." Which, by and large is your way of asserting your words are being unquestionably right, when they're not.

Personally, I think I'll trust my 21 years experience working with DirectX since it's inception and in combination with, Glide, OpenGL and PowerVR first hand, over yours.
Now, if you want to be a grown up and ask for an in depth explanation of why I don't see DirectX in general as such a great contribution as you and others seem to believe it is, I'll gladly explain, if not, it's no skin off of my back.

I like this one the best 

Thanks very much!

Of course I was asserting myself in that way. You pushed me into that direction with your very first condescending response, if you do not wish others to treat you like an ass, then do not treat others like an ass, yourself. - It's a simple concept, even children tend to understand it.
Also hilarious how you think your experience actually means something in this discussion. It doesn't. Nor do I even care about it, but to state you would prefer to listen to yourself than someone elses perspective/information is very telling though.

3dfx Glide is also no longer relevant, we are no longer using GPU's with fixed function rendering pipelines, plus Direct X started to beat Glide towards the end of Glide's life anyway, not just in terms of features, but often performance as well.
But if you think Direct X 6 era hardware with it's fixed function pipelines is somehow relevent to flexible, progammable architectures we have today, then you are kidding yourself.

OpenGL laggard behind Direct X for a very long time, adopting hardware features long after they became standard on GPU's and Direct X.

Microsoft, AMD, nVidia, Intel have worked together to set new standards for decades.
AMD sold their mobile efforts (Which were Direct X compatible with Direct X compatible features) to Qualcom, which then became Adreno.
nVidia pushed out it's own Tegra based on it's own Desktop technology.

Imagination used to be a PC company, they used to make desktop cards, then focused on lower power notebooks, before going purely mobile with it's PowerVR chips. Their last big foray in the PC market was Kyro, which has influenced their mobile efforts in big ways for a very long time.

Microsoft also has it's own research divisions dedicated to building new GPU technologies that will later get adopted by AMD, nVidia, Intel and eventually mobile chips.
For instance: https://www.microsoft.com/en-us/research/blog/microsoft-research-asias-guo-discusses-future-graphics/

Shall I go on?

Here, rather than be snarky i'll just outline why I say what I do and you can judge based on that instead.

Firstly, looking at the time frame of Steams development, Inception and eventual early success, specifically 2002 to around 2007 where the service had reached a point of having 13 million users and 150 games available for purchase.

During that timeframe the most commonly used OS was Windows XP, as Vista didn't hit shelves until late 2006/early 2007, and in that same timeframe OpenGL 1.4, 1.4, 2.0 and 2.1 released, at this point in time OpenGL was generally ahead of DirectX in featureset and performance, and was (and still is) Valve's preffered graphics pipeline.

With the release of Vista, Microsoft made a concerted effort to negatively impact the popularity of OpenGL by crippling support and changing the graphics driver infrastructure, in combination with developing Aero Glass in a way that prevented OpenGL applications from working correctly in windowed mode, as well as some other sneaky implamentations here and there, with the direct aim of pushing OpenGL out and forcing DirectX in. This largely resulted in them only allowing OpenGL 1.4 applications to support certain operating modes, anything newer would not work (a demonstration of willingness to taint the pool), Microsoft of course had been trying to kill off OpenGL for a long time up to that point, but it was the first time they had been blatent in their attempts, previously in 2002 when Microsoft had acquired a portion of SGI they had used that acquisition to claim that they had patent rights for the ARB_vertex_program extension, thus they tried to levy licensing from anyone utilizing it, this was also clearly an attempt to cripple or kill OpenGL.

Now we need to keep in mind here that OpenGL is an open-platform pipeline, where as DirectX is exclusive to the Microsoft ecosystem, so killing off OpenGL would have placed a monopoly on graphics pipelines and game support on to Microsoft Windows based systems, and best-case moving OpenGL support for systems such as Linux to non-free repositories where a license had to be agreed upon, or worst case (and more probable), revocation of OpenGL's use entirely.

But the primary point here is that valve largely relied upon OpenGL in the opening years of Steam, and even today, long after DirectX eventually pushed ahead with DX11, OpenGL still holds it's own against DX12, and it still the preffered pipeline for Valve.

But WHY did OpenGL lag behind exactly? was it because it wasn't as good? not at all, Khronos group, the company behind OpenGL announced in 2014 the development of the Vulkan API, one year after AMD began work on Mantle, realizing that a full rewrite and new approach was needed, given that both OpenGL and DirectX (all the way up to 11) were designed primarilly for single core, single GPU systems and only had patched in supplimental support for multi-core/multi-gpu systems, thus did not take good advantage of more modern hardware, so while development of OpenGL was still in progress, there was a shift in focus from adding entirely new features to simply adding comparative features to maintain synchronicity with game development in terms of the released game.

But the stupid thing is, that even today, OpenGL outperforms DirectX (all the way up to DX11) because it's a much more efficient, lower level pipeline in comparison, it's only DirectX12's rework to approach modern hardware directly that gives it the edge, and edge both Mantle and Vulkan have sidestepped in being even better performers, if you take one of valves games for example, Left 4 Dead 2, it runs better on linux via openGL than it does in windows on DirectX, significantly so.

Ultimately though, valves heavy dependance on OpenGL during the early days of steam demonstrate that it's success was largely down to their own work and little to do with Microsoft, pointing to the latest versions of DirectX having more features than the latest OpenGL as reasoning for why Valve was successful 15 years ago doesn't make sense, and while the majority of valves early games supported DirectX too, just like with current desktop and mobile hardware, having support for something doesn't mean that it's success should be attributed to the pipeline it supports, especially not if that's both not the only pipeline nor the preffered pipeline of the developers at the time, heck in Half Life, one of the cornerstones of modern PC gaming, you can't even select DirectX, it's software or opengl only!

I could get into all the various revisions of DirectX and how many of the changes/features broke older applications built for earlier revisions, or how some of the feature additions were put in place specifically to take advantage of certain modes and support in the OS while preventing other pipelines from doing the same, or how over the years, Microsoft have actively engaged in sniping OpenGL API developers to take them off the project and put them on DirectX, but none of that would do anything but further underline what i've already said.

I love you. Kiss me. 

How about credit them for bringing the PC gaming ecosystem to consoles? Huge online Multiplayer games, harddrives, proper internet etc. They have done alot to the console marker where as Sony normally just take what Nintendo and MS bring to the table and try to refine it.

MS always lose? Amazing how there considered as one of the most successful companies in the world. I didnt know success happens when you lose all the time.

Isnt Direct X the most used gaming API in the world? Oh wait it is..

I'll credit them all day long for doing things like standardizing the addition of ethernet ports and hard drives, rather than them being optional additions (ps2 hdd/network adapter, dreamcast BBA), but huge online multiplayer games was something Microsoft co-opted from gamespy.

As for Sony taking whatever Nintendo/MS have done and trying to refine it, don't you mean Microsoft saw the success of the PlayStation 1 and felt threatened, releasing the Xbox in response to it? (as history has well documented).

And yes, in the console gaming sphere, MS have always lost. Name a single Microsoft console that has been the top selling platform? (Hell, name a single Microsoft console that didn't end a generation with the lowest worldwide sales).
As for DirectX, yes it indeed is, now. but when talking about the success of Valve with Steam, you have to look at the window between Steams launch and success, a time in which the majority of games used other pipelines in addition to, or exclusively from, DirectX.

Crediting Microsoft for their API's current status, for the success of software that became successful, 15 years ago is myopic.

Whether you like it or not, Microsoft's Xbox platform has lost it's way, be it a combination of terrible PR and planning or the fact that they wasted money on, and tried to push, Kinect not once, but twice, and now survive in the console gaming market largely on the backs of diehard fans and their fast aging franchises.

Nintendo and Sony are simply better at making gaming devices and games in general.

No. Xbox hasnt had the most sales in a generation however there 360 was more successful than the PS3. It gave Xbox a third of the gaming revenue, it was selling at its best prices, it was cheaper to make, and it was a developers dream *cough Cell*

To say the PS3 was more successful on its last couple of years is sad. MS stopped focusing on there 360 for there XB1 and saving there games for there next launch eg Forza 5. Its like if Xbox decided to keep the OG xbox on the market for 20 years and it outsold the PS2 its not what i consider being more successful. 

So for Sony making better games and systems? Very debatable. Both Sony and Nintendo cant compete with Xboxs strenght. There online network, there controllers, Xbox has the better FPS franchise etc. Sure Sony and Nintendo have there strenghts too. 

As for hardware? Well the OG Xbox and 360 says otherwise.