I've had a similar experience, except in my case a bunch of the bigger posters found they no longer automatically got a ton of attention on Mastodon and without that dopamine feedback loop they just gave up microblogging entirely.
Most artists I follow also just dropped Twitter entirely and are on Instagram exclusively now (much to my dismay, the Instagram UI is nails on chalkboard to me.)
It's interesting how differently the experience has turned out for different crowds.
I've seen numerous anecdotes from more technically-inclined types saying that their Mastodon posts not only get greater engagement than their Twitter posts did, but that the average quality of engagement is much higher and closer to an actual conversation.
I imagine it depends on how much you played the advert game. While twitter is massive, it is very easy to get buried if you don't play by their rules. Techy posters are the antithesis of that algorithm: focused on text more than pictures, trying to deliver links to non-mainstream sites or personal blogs, rebelling against authority, probably sparse in their use of hashes.
So I can see a more intimate setting benefitting them more than a more traditional content creator who is already used to all those hoops.
Most artists I follow also just dropped Twitter entirely and are on Instagram exclusively now (much to my dismay, the Instagram UI is nails on chalkboard to me.)