The casual gamer is perfectly happy with cookie clicker or Fortnite on mobile. 2D games should be able to run on almost any platform and 3D games can be toned down until they run well too. The only type of gamer that isn't served by the things above is the "core" gamer that wants high fidelity 3D graphics and real time experiences. Really the only need that streaming serves is to make DRM possible which means the companies want to have complete control over the user experience and they certainly are going to abuse that control as much as they can.
Most 3D games don't even have to be toned down. Because if you stream video, you don't care if you send a video of a 2D game or a 3D game. And that's the main appeal of such services: you don't need to spend large sums of money to be able to play modern games in high or ultra high settings. All you need is a beefy internet connection with low enough latency.
