You can’t argue that the guy saying he has a problem with Google’s sign-in specifically has a point and also say that the data mining happening within Plex is WAY more intrusive.
Those are not mutually exclusive statements. In fact, mostly it just makes you an idiot for not having a problem with either.
It is worse than an auth method that isn't maintained by a known data whore like google. It's substantially worse when you're using it with another data whore service. For those of us who administrate remote services and care about not being beholden to google's data addiction, it is absolutely not a good thing to provide it as the default auth method, which is what the OP was saying. Even if jellyfin included it, I would immediately disable it. Especially since, as a server administrator, I have a vested interest in keeping the activity of that server private. Even if the specific details of the media on it aren't exposed, I don't want any party with conflicting interests to my own to know what users are associated with my server. Just having a dozen or so users connected through jellyfin to my IP would be enough for a motivated legal entity to look at me, and I have more than just a private media server to worry about. Is it likely to happen? Probably not. But why would I even risk it?
If you have a source for how apparently US law is directly applicable to any country they have a trade agreement with feel free to point me to this insane new paradigm of international law, though.
I don't have a source for you, but typically using a US-based platform can give US authorities a jurisdictional hook, especially if the rights holders are US-based or can show commercial harm. That is why US based web services are extraordinarily strict with all of their users, even those who live outside the US. I'm not even saying it's common, just that it could happen. I seem to remember operators of p2p services getting nabbed at customs while traveling back in the day - it wasn't illegal where they were, but it sure as fuck was in the US and they were extremely interested in putting the kabash on it.
No question that plex is a more convenient service, but if you have the tech literacy to manage something that's completely private that is only marginally more complicated, why the fuck wouldn't you? Then again, maybe if you think you're more tech literate than you are, it doesn't seem all that simple.