I'm against this. It limits travel distance and forces backtracking. It would also encourage more immersion breaking gimmicks like long distance orders. I prefer being a traveler across faerun and eventually the other realms freely without a gimmick like that. The camp is enough.
Imagine being right near a boss in the astral plane and then going "oh wait let be backtrack to a boring fort to talk to ncps about nothing". Pathfinder kingmaker and especially dragon age has these and they were the most hated parts of the game. It breaks the flow waaaaaay to much.
The camp is kind of guilty of all this already and is already rather immersion breaking. A keep might make it worse, but it is kind of bad already.
