Hit points are only one measure of full combat utility, as are spells, combat dice and other short rest attack options. None of these are reduced in effect by hit point depletion.
If you're going to play hit points as meat, I would either add a death spiral or prevent players from meta gaming their hit points, ie controlling character action on how fast they fall to 0.
Why? Players already meta game decisions on every single aspect of character features, abilities, and mechanics. What makes hit points so special? It's human nature, even for those roleplayers who purposely try to ignore that stuff. It's a game. Players should typically make PC decisions based on the current situation in the game and based on the rules. It's not metagaming to not attack a dragon when you have one hit point left. It's smart play.
Been using hit points as indications of damage since 1E. Works fine. Hence the terms heal and damage all over the PHB, MM, and DMG in every version. Just because I view a decrease in hit points as damage does not mean that I think that other abilities should be penalized (although I played for many years with a bloodied system of -1 or -2 to all D20 rolls when half damaged).
I use injuries on top of hit point loss, fwiw
Just my 2p
Cool.
