Yeah, that surprised me, actually.
I just took Mastodon for a spin only a week or so ago, and it felt much less active than most of the communities on here do. Just my anecdotal experience, though. I couldn’t find more than a handful of Twitter-migrated accounts on Mastodon that I cared to follow. There just wasn’t much happening on there that I’m interested in when I last checked. I’ll look again.
Another hot tip: don’t refer to people as “normies.”