Have a look at this post, we had a similar discussion there: https://lemmy.world/post/3074361

Long story short, the platform still needs a bit of work before being able to really move communities. Some examples exist (lemdro.id, piracy, startrek) but those are tech savvy audiences, there would be a lot more friction with more generalist communities

Lemmy.world holding such a prevalent place in the Lemmy/Kbin part of the Fediverse makes it a major single point of failure.

They should still be the newcomers instance, but communities and users should migrate to other instances to increase the resilience of the Fediverse.