Well the world is upside down and backwards, maybe even flat, so this seemed to fit the bill. Let's all hope I'm very wrong though, sarcastic or not, for the sake of gaming kind.

They do allow it. The PUBG devs are considering adding cross play between steam and xbox.

Edit: Rocket League on steam also has cross play with xbox.

Edit 2: Killer Instinct also has crossplay between Xbox/Steam/W10

https://news.xbox.com/en-us/2017/09/07/killer-instinct-cross-play-steam-xbox-one-windows-10/

That is entirely on Valve, not Microsoft. Just like no crossplay on PS4 is entirely on Sony and not Microsoft or the developers. But Rocket League has crossplay, so maybe the developers are just pricks. So long as the games also have an option to play with just your platform, cross play should be a feature everywhere. Because some console players may want to avoid the superior and much much more better PC players.

Very stupid if true.

As others have pointed out, MS does allow crossplay with Steam, and Sony isn’t under fire for having crossplay, they’re under fire for holding people’s Fortnite accounts hostage.

Sounds more like Steam than MS. Afterall MS just end up releasing there games on Steam to compensate

PC has the advantage of Keyboard +Mouse control scheme, which is vastly faster and more precise than anything possible with a controller, especially in strategy games and shooters. Hence why these kinds of games don't allow crossplay with PC, because console owners would get pwned from here to yesteryear and back against PC gamers. The 2008 Shadowrun First person shooter tried it for instance, but even the best console gamers were no match to for even PC gaming  shooter noobs due to the much better controls of the latter.

In any other type of games, crossplay with PC is possible, just check Rocket League for instance

Microsoft asked valve for age of empires 1 remake cross-play and valve declines, else the game would have been released on steam so this isn't in any fact shape or form the fault of microsoft.

They do allow crossplay. The problem here is that right now there isn't a solution how to implement Xbox Live and Steamplay communication on MS or Valve servers. So, if developers want to add crossplay they will need to use their own servers. This is how it works. Most likely Ark devs don't want to pay for their own servers and decided to use Xbox Live for Xbox/Win10 and Steamplay for Steam version which means no crossplay. I doubt we will ever see crossplay in games that aren't really huge.

How stupid is it that there are multiple online platforms in the first place.