@ottocrat
I think there is a piece missing from your model here.
I've been on Mastodon for years, and there was plenty of content on here that had nothing to do with the migration before November 2022, just with less volume, obviously. Even after the migration, the people who are here to talk about things other than social media are still talking, it's just if you fill your feed with people you knew from Twitter, people who are part of that migration, that's what they're going to be talking about. This happens in waves as Elon keeps doing stupid things that make people come here from there, which is good, because people coming here and people discussing the billionaire problem is good, but there is more to see.
Whenever I see someone say that there isn't content here, I explain to them how their feed is populated, suggest they start searching for things they like, then follow the people/hashtags with that content. That populates the feed with something other than Twitter.