that doesn't hold for other groups. people that don't want to think about internet application protocols (most people) throw up their hands and leave at the first notion of needing to choose an instance or needing a JS bookmarklet to follow someone not on your instance
plenty of those people are experts in their field and write interesting content i wouldn't otherwise encounter, but they aren't migrating to mastodon because of that, and there's a decent chance they won't migrate anywhere and will return to sharing their work in niche walled garden academic journals and conferences
sure, mastodon maybe keeps out the garbage firstnamelastname9023285023 accounts that do nothing but send low-content replies and retweet inane celebrity(s' social media managers') posts, but it's keeping them out because only a very specific population will bother to get in, which is a bad filter