I'm throwing this idea out here because I've recently seen/been in situations where either I was in a streamer's party, or caught up in a large group situation (like when new content drops) where too many players in a small area make both finding the content NPC's and party members unable to login to the same server, and people constantly doing things to obstruct the streamer's vision in the world.
To me, the obvious solution is to have a Paid "login to private world instance" where the server generates an invite code for the player paying for it, and it would isolate the player to an instance of the world map they are on, and the people they invite or are in their party/company would automatically move to whatever zone they are in with them when that player is on, denying the teleport prompt drops them back to the regular instance of the world. Duty finder would work the same as before, but only match players in the instance. The person paying for the instance could also "disable mounts and minions" to allow more people into the instance.
I'm not advocating this for RP, but clearly that would open up a lot of possibilities, positive and negative. Mostly just looking at a means to both allow streamers to play the game with their viewers without causing a disturbance for the rest of the server, especially when that might result in 1000 viewers trying to join the same server at once.