I think a big help to avoid this is if any “official” apps automatically point to something like lemmyverse search or Fediverse Observer rather than Join Lemmy or any single instance.
Mastodon.socialwas already by far the largest before the only app named “mastodon” available in the major mobile repositories was built to automatically have you create an account on mastodon.social to “Make it easier for the normies”.

The fact that I dont’ even know the name of any lead developers of #lemmy as opposed to /u/gargon@mastodon.social is probably a good sign too.

I think that’s against the plan with Lemmy and distributed instances, but they can improve sign up, and make it possible to migrate your user between instances, or do some unique username across all instances.

A cool feature would also be that a user could backup all their posts and votes.

Simple fix, just don’t join big instances, create new communities on small instances and self-host. If everybody does so, nobody has an interest into coercing users in a hermetic system, because they have far more to loose through possible defederation

Since people post to channels that you can search for and subscribe to, there is no incentive for that to happen.

The whole system is crap.

We should have gotten something that’s actually decentralised and P2P like Aether.

What we got was centralised servers + a glorified RSS feed that enables even more echo chambers than Reddit did… The fediverse is doomed to remain irrelevant imho