As far as I can tell, Mastodon is nothing but nerds, which is what I like about it.

Anyone can get past a dog, nobody f$;&&) with a lion.

Anyone can get on mastodon, nobody f&)@) with emacs.

But seriously the barrier to entry is high enough you will only get the true geeks.

A barrier-to-entry isn't necessary if no non-geeks want to join in the first place (which is, IME, true of Mastodon). Mastodon has successfully made itself a place that no non-geek would ever _want_ to spend time on anyway, so no barriers-to-entry are necessary to maintain that state.

(You can decide for yourself whether this comment is praising or criticizing Mastodon)