And now, Twitter blocks unregistered users, forcing us to sign-up
Me who've left my Twitter account to rot (and possibly nuked by Stealon Muskrat): Eh, I guess I'll just not.
And yeah! I don't think it'd be long before those that you've mentioned do the same thing: keep everyone not already logged-in out, and preventing anyone else any access.
Yeah, and once people are locked in to the various walled gardens, the enshittification will accelerate. On top of that, they're making the costs (the effort, etc) to migrate to other services and environments really hard, keeping people trapped.
At least this dystopia isn't that boring, for now, at least.