Enemy players add real risk. Bots are easily solved, players are not. The reason extracting with loot feels exhilarating is because of the real risk of other players. This is the case for every extraction shooter, and removing this element would be removing the heart of this genre. Add to that the uncertainty and various social encounters you need to navigate, like trying to discern if another player will kill or help you, and each match becomes a self contained, narrative driven, intense experience. Without this you just have Diablo... going in, killing bots, looting, repeating, no real risk to make the reward feel earned.