That's not entirely correct. Mastodon already implements a feature to migrate to a new instance. Also there is a draft for identities that are not bound to an instance.

You can't even post titties on Facebook/Insta. Big corps are intensely politically motivated, they succumb to American prudery through advertiser pressure.

Even the more centrist tend to block instances. Especially because the others are politically motivated. Who in the center of the political spectrum would want to federate with gab for example? The same goes for the other extreme, like some instances which are full of tankies. When you federate with them you can't have a single news topic without getting "NATO evil, Putin great" pile-ons. It derails every discussion.

One of the nicer centrist instances is Beehaw and they defederated a lot of stuff just to keep the atmosphere alright.

I used to think it was a bad thing when instances defederated each other but since I saw the above happening I agree with it.