I don't think this should be a rule though.

For example, MHFSilver and Papo manage the Ty series leaderboards, and MHFSilver has been a member of the community for a long time, but he doesn't have a time on the leaderboards, and they both manage the boards for the other 2 games in the series, of which Ty 2 has a couple of any% runs, and as a community we're working towards 100%, and Ty 3 has an active runner but I haven't been able to get in contact with him yet to post his times. There are definitely some communities that are small and don't have very populated leaderboards in which things are being managed well within the community in terms of categories and overall stuff.

A lot of the moderators are series moderators who currently get power over all the games in the series because we don't have people to handle all the individual games right now. (There's an option for the game moderators to turn off transferring series moderators.)

It's obviously preferable to have someone that runs it handling it, but absolutely requiring it won't be ideal. Picture a case where maybe one person in the universe runs the game and isn't a member, but a second person knows the game decently well and is willing to moderate it.

We can shift people around as necessary to get better representation in charge of boards. There's no way to always get the right people in charge the first time. Like you said it's an inherent problem that we can only solve gradually over time.

Categories are all individually added by moderators and will probably largely stay that way. There may be a "request a category" type thing eventually.

Also we don't have private messages yet, so solving some of these issues on a large scale may not be the smoothest for the short-term.