Glad to see you've already be thinking about it, and those are all excellent points. It is hard to make a system like that in a way that precludes it from being gamed, and voting would require tracking user reputation in some way as well. I imagine it's something that would need to be tried and refined over time if you do decide to give it a shot. No matter how good the system is, people will continue to look for different ways to game it. So, it's always going to be an arms race between loopholes being discovered and addressed.

I also very much agree with the emphasis on active users over subscriber counts. Ultimately, it's the people who actually participate that make the community what it is. Although, jumping communities/servers might be a bit trickier once the scale grows. And this would be an important aspect from activism perspective. If there were a million active users in a community, and it was being used for real world agitation and organizing, then a rogue mod could potentially do a lot of damage.

Thinking a bit more about it, I wonder if a simpler solution than voting could be to allow making communities with restricted mod powers instead. For example, could make it so that community can't be deleted, mods can't take it private, etc. And as you note, if the admins are actively participating then they can be used as arbiters for issues like rogue mods. You're right that this is a big difference from Reddit, and if server admins go rogue then there's really nothing you can do about that with software anyways. So some trust is ultimately necessary.

I just wanted to float the idea, and I'm also not sure how workable it would be in practice. It's obviously a bunch of effort to implement and test a feature like this, so it's worth thinking about the merits before investing the time into implementing it.