One of their mods, https://lemmy.world/u/sabbah, currently mods 54 communites despite only being on Lemmy for about a month and has never posted on c/documentaries (except for his post asking for people to join his mod team).
Final: Was going to create an issue for this on the Lemmy github, but I browsed for awhile and found that it had already been done. If anyone wants to continue the discussion there, here it is - https://github.com/LemmyNet/lemmy/issues/3452
Perhap we need another issue for the problem in the original edit (It being impossible currently to remove a 'founding' mod without destroying either the community of their account)
If you're interested in one of those communities and the mod is still active - pick it up with them first. In cases where the mods have abandoned the community completely we as admins can transfer the community to a new mod/team.