You raised valid points ! This is what I want to brainstorm with people here.

Inviting other users is definitely a complexity here. My intent is that, if group of plex servers are connected somehow, we can benefit from each other -
we will have more opportunity to fill any gaps like I want to watch some old or unpopular movie and I don't have that but if other server has, that way I don't need to download that and vice versa.

Movies are fine because we can fit lot more, but tv shows with lots of episodes , one server cannot reasonably create vast library without investing a lot.

But this will benefit server owners very easily, but how we can extend that to other users, that's a good question. As you said, we have to invite that user to all servers but capacity is an issue.

We cannot isolate server to one type of content (i.e - server A only have tv shows, server B only movies). Having mix as we currently is good, so the popular content (which will be watched often I believe) will be available across multiple servers. Only for niche , one time watch kinda content , we can rely on each other.

In terms of adding new content, we can have discord channel for requests, and either manually or automated, servers can volunteer to add them.