For big ones it is a time commitment thing, but for small ones I have tried to do my part.

I have found I generally have the time to act as a caretaker for some small communities, and there are more than a couple communities out there which have lone creator accounts that have been deleted and are essentially unmoderated (outside of instance admins).

I found a couple of these, !canada@lemmy.ml and !firefox@lemmy.ml, and decided I could help watch them as a result.

If they are fairly small I would definitely recommend it to anyone else - for me, by far and large, I find that the users who engage with these communities are really very respectful and create good conversation about the topics, which makes my role very simple most of the time.