Well that’s because Mastodon has many shortcomings. Like the search sucks. It’s hard to find people to follow without asking people for recommendations. Mastodon is scarcely a Twitter replacement; it feels like it was built to create extremely insular communities. Like Gab and Truth Social run on Mastodon’s software.
Unfortunately, Mastodon’s lack of features makes it hard for normies to use and it will not see mainstream adoption. I hope normies get a decent Twitter replacement.