I saw a similar thread on Reddit itself. They had several sources that claimed mastodon had "failed to convert Twitter users", and therefore the fediverse was a waste of time and would never catch on. I just chuckled because the longer they stay away, the better the fediverse will be (for me).
Some that I have come to enjoy on "That other site":
Facepalm InstantKarma KDE Linux (although I appreciate there's a community for OS) ObsidianMD StarTrek Buddhism Astronomy Motocycle (and/or MotoUk) Meditation Archery Rollerblading