But that wasn't my argument at all. In the best case scenario it is as good as a console. In the worst case scenario it is unusable.
In both of those scenarios my PS4 or laptop, or Switch or whatever will still be able to play whatever games I like regardless of how spotty my internet connection is. I don't have to rely on an internet connection that for the majority of the world isn't as reliable, consistent or affordable as you're making it out to be. I don't care about concept, I care about real world applications. I've seen plenty of absolutely outstanding tech demos that totally fell on their fucking face in the real world. If you need some recent examples, see Titanfall's release and claims that the game wouldn't be possible "without the power of the cloud" or better yet, check out Microsoft's claims about UWA. That shit never panned out, but the tech demos sure looked impressive!
But, hey if you want to count on google and the internet totally for your gaming experiences, that's cool man. Just don't try and dunk on anyone that points out the downsides of that. There's plenty of very valid concerns when you look beyond the presentation and get into the meat of real world applications and issues that an average user will have to contend with that they will not have to contend with on a traditional piece of gaming hardware.
But, I mean, that certainly is your argument. Your next sentence revealed just that; in the best case scenario, it's not merely as "good as a console" - it's tremendously better than a console specifically and exclusively because it is not a console. In the worst case scenario, it's just as unusable as, for random example, a PS4 in an airport, a Switch in a small pocket, or a laptop when trying to have a 4K 60" screen.
In those hyper specific scenarios, the platforms are completely unusable as well, but it would be silly to present those as cataclysmic checkmates that prove why those platforms are not viable or less viable than platforms than can do what they can't. In most scenarios, most people have access to good enough internet for that specific con to not be an issue most of the time, and everything it can do to make up for that deficiency surpasses anything any current platform can do from a fundamentally conceptual level.
It's not just that it's so convenient and instantaneous to play, but that it also has power matching and possibly surpassing the rumored specs of next generation consoles with the ability to constantly improve computationally constantly and with not so much as a software update needed on the user's end, let alone a physical or financial change. It's that it's a platform that is fundamentally un-hackable because the software and hardware is never localized or centralized. It's the possibilities that having a platform where the the client and servers are not connected via the internet the way they must be on consoles, making the standard multiplayer experience not dependent on the client with the slowest connection because both the game client and server are localized to Google's networking backbone before hitting the internet. That fundamentally changes online multiplayer latency in a way that literally cannot be replicated via physical consoles due to the very nature of consoles. The list goes exceedingly on.
I understand having a wait and see attitude from tech demos and declarations. I don't think there's a single thing MS said about those games that "wouldn't be possible without the cloud" that actually exist in those games specifically because they just aren't using the tech. Stadia is different though because it's literally only cloud tech. There isn't anything else they can use but cloud tech.
I'm only ducking your "downsides" to the same degree that I would duck someone who purports the "downsides" of, again another random example, a PS4 in an airport, a Switch in a small pocket, or a laptop when trying to play have a 4K 60" screen. I guess not being able to play a PS4 in an airport is a "valid concern," but I don't think it's one "valid" enough to discount the tremendous utility of that very same PS4 in nearly every other relevant scenario, in which cases it currently potentially excels far better than any other platform that can actually be played at an airport.
The airport needn't be the hill you choose to die on is all I'm saying.
Tremendously better than a console? Well that remains to be seen, doesn't it? Look. In an ideal world with a steady, reliable, uncapped internet connection whereever you go, then sure, this might be able to offer a slightly worse gameplay experience than a PS4 or Xbox One. But that's not the case.
You can act like it's "no big deal" that wi-fi is still pretty shitty in many places no matter how urban, and cell is not only shittier, but often capped. But the only thing limiting me playing my Switch anywhere on the planet is the availability of a power outlet, and even then, it should be fine if one is an hour or two away. Stadia, on the otherhand, will offer a poorer single player experience if my wife decides to watch Netflix. It might not be playable at any time in any college dorm, or foreign military base. It certainly isn't usable in a place with no wi-fi or cell access, and well, that might not be an issue for you, but it will be for far, far more people than you imagine. These are real world issues that every day people experience every single day, Sure I might have brought up airports, but that's only because I recently went on a flight with a 4 hour layover, and totally gave up on trying to play an online race of mario kart because the connection was so shitty, so I stuck to single player gaming for the time I spent there. If I was relying on Stadia for my gaming experience I would have sat there, bored out of my trees - top that off with the experience I would have gotten while flying and that's a whopping 9 hours of game time I got in when I would have gotten nothing out of Stadia.
As for "only possible with the power of the cloud" it was collision detection/physics/intensive calculations that MS claimed required cloud-based processing in order to accomplish. As it turns out, they were either blowing smoke up everyone's asses, or they scaled back the game to not require it because you know, the Xbox one was no longer "always online". But as far as the presentation goes, it worked great! Just like Stadia...
I think I need to emphasize, I had this exact same conversation with people when the Xbox One was initially announced, and that was even less of an issue because it was a home console and internet is more reliable and accessable in homes than possibly anywhere else in someone's lives. The internet tore it to shreds, flat out rejected it, and Microsoft had to scramble to put that genie back in the bottle. Now a little over 5 years later, google is gambling that the gaming community has effectively pulled a 180 on the whole thing, and MS was simply "too early" with its gaming model. Well.. we're gonna see about that.
By all means, put all your eggs in the online-only streaming basket. Have fun with that experience you're convinced wouldn't be available anywhere else. But just remember every time that experience is hampered by a less than ideal internet connection that its a sacrifice you were willing to make, but didn't have to.