> We can already see hints of this in the fact that their terms of service prohibit inciting terrorism or acts of violence – issues that 4chan/etc deal with by allowing it, reducing their reach, and Twitter (attempt) to deal with by banning it, increasing their reach as they provide a "safe space".
Inciting terrorism or acts of violence are typically crimes. If Parler's position is to disallow criminal activity in its TOS, that's one hell of a limiting principle, especially compared to Twitter.
In my (right-wing) experience, Twitter became a toxic place after the "trust and safety" moderation was adopted. Before that, when it was "the free speech wing of the free speech party," users with ill intent could not attempt to get others deplatformed. Today, we still have harassment on Twitter, but with the added threat of user mobs brigading those who have the wrong opinions.
The one point I think is important is that the "blue checkmarks" indeed demand protection from the unwashed masses, and that is why the rules are so selectively enforced and biased. Journalists and public figures are typically of one political persuasion (in the US at least), and sometimes perceived alternative ideas as "violence" or just wrongthink no matter what.
Parler had to avoid being beholden to its highest-value users in this way. If Twitter were not so intolerant, I might use it more. But these days, it feels like you need to walk on eggshells to avoid a shadowban.