Simple answer: the fact that we cannot play out in reality the game's physical dimension at the table, due to a combination of player (lack of) abilities commensurate to their PCs, physical space limitations, and in many cases the laws of whatever jurisdiction you're playing in.
But, we CAN play out the psychological/neurological dimension* to a much greater - ideally, almost total - degree; thus why not do so?
* - i.e. conversations, thoughts, opinions, decisions, non-physical interactions, feelings, emotions, etc. etc.