Echo chambers breed extremism, and ones with a low barrier to entry and a smokescreen of "saner" content are much easier to bring in new users.
If it's difficult to use the thing and the content skews more and more extreme, existing users may continue to get more radicalized, but new users don't offset attrition rates and eventually it dies off.
Like with the Pirate Bay, the demand for Parler is already there. Outside of being declared illegal, Parler soon come back online or another app/website will take its place.
If it's difficult to use the thing and the content skews more and more extreme, existing users may continue to get more radicalized, but new users don't offset attrition rates and eventually it dies off.