Yes… at some point you can’t physically pack any more into a room!

Though in the domain of optimal transmission speed/quality, very quickly yes, less noise is better! So you would want few transmitters, but having many receivers in a array would be a huge boon… so really, you could use as many as you like, but with rapidly diminishing ROI. At some point a 8x8 MIMO isn’t much worse then a 16x16 MIMO for a small room.