@href I resolved the email domains of 120 recent accounts.
Result:
1 mxsrv.mailasrvs.pw
1 127.0.0.1
The rest is okay (lot of gmail, hotmail, protonmail, riseup and tutanota). A few suspended themselves.
I think a lot people try Mastodon out and in line with our consumer culture, they make an account, forget about and move on. Some of them remember and revisit the instance the next day, week or month(s).