I’ve been on Mastodon for over a year and the content simply isn’t there. Several of the people that I follow on Twitter have tried moving or duplicating to Mastodon. They’ve had a fraction of the visibility and engagement from commenters that they would get on Twitter. Invariably after a few months they have essentially given up on it as a primary medium. For me the discoverability is essentially non-existent, which I don’t think is helped by the idea of it being based around instance-local communities, which have no meaning when you’re looking at something like Twitter.