On Mastodon, there's general agreement that better account migration is vital but it hasn't been prioritized over the last seeral years (although at least you can take followers with you). One of the factor is that the Mastodon dev team also runs the flagship instance, from which a lot of people would migrate it if were probably easier ... so at some level it's not that surprising they haven't prioritized it. We'll see what happens here.
Out of curiosity, what's the beehaw philosophy that they're so open about?