It always amazes me how much the people who want to talk about immersion also want to treat HP like it's a video game life force bar and then they act like anything that's incompatible with that view is what's being unrealistic.

THIS. The video-gaming of tabletop really annoys me. But I am also going to be the one who argues that the immersiveness of a game is only as deep as its DM-- no rule, or lack of a rule, is going to do it for them, or for the players for that matter.