There should be a kind of “sorting hat” personality test to attract the interest of prospective Lemmy joiners. People who love solarpunk stuff, for example, would easily find their home in slrpnk.net. Set a link to it on sites like join-lemmy.org to make the fediverse more approachable to casuals.
I feel like the functional differences between instances are:
When I first immigrated here, the most popular platforms were Lemmy and kbin. I liked the kbin interface more, so I started on kbin.social - which folded after a while. So I switched to fedia.io, which runs mbin, a kbin fork.
None of this has anything to do with “aligning a personal identity with an instance.”