Like this product literally depends on which godawful modem your ISP sent you when you first got service.
I've played multiplayer FPS games on a home-made setup with an AWS VM with GPU and Steam streaming (using a VPN to make both machines appear to be on the same LAN so Steam streaming would work).
This worked well, but only because it was on an enterprise-grade leased line with consistent 1ms latency to the AWS datacenter, and all wired (good wireless gear might've worked too, but forget about trying that on garbage consumer-grade hardware like your typical router or mesh Wi-Fi setup).
Is it technically possible? Yes and it works well under optimal conditions.
Is it possible for the average user who doesn't have good equipment nor the budget for it? No chance - it's a recipe for disaster. Those who do have the budget are better served by just buying a gaming machine and running the games locally.
Games streaming can be a value-add to a good ISP (such as Google Fiber) whose network actually permits this, but don't expect it to work on the majority of residential connections. The vast majority of them suck (whether because of the ISP's network or the customer-premises equipment), people don't know they suck and have no easy tools to test that, so they'll end up blaming the game streaming provider when it inevitably doesn't live up to expectations.
Until good networking setups become commonplace, game streaming will remain limited to a very small niche that have serious networking setups but for some reason don’t have a local gaming machine.
It's unacceptable even with a 1ms link (because of the extra 2-3 frames of latency that get buffered in) for hardcore players in some genres. Even if they can't see the difference, they'll feel it when they miss shots in FPS games and links/confirms/parries in fighting games
Unfortunately, most of the people here and in the industry making these streaming products are adults with real lives who don't understand how bad game streaming is for hardcore players
Not only that, but a lot of AAA games nowadays have super long animations, tons of post-processing slapped on the tail end of the rendering engine, etc, so you end up with 300+ ms from "button pressed" to "something happens"
My understanding is that Stadia and most other game streaming providers run PC games which are developed with the assumption of precise mouse/keyboard inputs where there’s no assistance.
For example, Comcast over-provisions their upload so much they cannot even advertise what it is. They will sell you 2Gbps download and never tell you the upload. Which I assume, based on experience, is 20Mbps split over a neighborhood of 500 houses.
Contrast to whenever I have used a symmetric fiber connection that advertises 1Gbps/1Gbps, I can actually sustain close to both of those and at sub 5ms latency. Whatever the theoretical promise is, I assume non fiber non symmetric connections are simply low quality (in the USA).
Edit: Nextgrid showed up as I was typing this and set the record straight. My faith in HN is restored.
Unfortunately there is no user-friendly tool to test for this. Most tests focus purely on speed, which can be tricked by various packet-loss-compensation algorithms, so you can score a "perfect" 1Gbps speedtest despite the connection cutting completely for a second.
Sometimes I forget that was ever a thing!
These sorts of EULA arrangements are essentially the foundation of almost all modern media consumption - if anything Stadia is on better ground than most since it's not just a DRM layer like Steam or iTunes. If Steam disappears, I have a bunch of entirely playable game files on my computer that I can't use. When Stadia shuts down, you have a client for nothing. You're not paying $60 to own a copy of a game, you're paying $60 for an unlimited term license to play the game on Stadia's servers. Legally, it feels odd to claim in court that that should be the same as a purchase of the game in some other method. If Google had turned off Stadia, but transferred everyone's purchases to Steam or EGS, that wouldn't be providing the same service you purchased from Stadia.