The game that sparked this movement was shutdown 9 years after it came out, and had 3 months notice.
Even if you could host it on just one or a few machines, if you sign up for one server and your buddy joins another, you can't do raids or anything together. And each of these player hosted servers has a player limit.
Anti-cheat that isn't being actively updated is next to useless. Community servers would be botted to hell.
The game requires a maps tile service. Expecting Niantic to provide map tiles for anyone to download is insane. They might not even own the rights to do that.
It's virtually impossible for Pokémon go to remain in a "reasonably playable state" after the servers shutdown.
I'd certainly encourage a more sustainable solution like a self runnable server, but I'd settle for replacing the word "buy" in marketing with "license" or "rent" with actual terms other than "until we decide to turn it off".
You don't get to make software a "license" but then not have any obligations to your licensee.
I agree that clearer language about what you are actually "buying" would be good for consumers, but it's tangential to Stop Killing Games.
In the specific case of Pokemon Go, and with end-of-life plans in mind, you could probably design the game around that expectation. GDPR has had similar consequences, at the very least.
Also, this text is not law. This will be negotiated and I doubt the gaming industry would leave the initiative as-is.