What is so hard to get, on HP? They are just an abstract endurance metastat, until they reach zero, then they show actual mechanical effect. Even then you still could say you just lost consciousness, no big injuries visible.
Hit points are a stat which reflects how long a character is likely to survive a combat.
Hit points (especially their loss) are not an indicator on your PCs current physical state. It is not that you even have to bleed from a single wound just because you only have 1 HP left.
Look at the good thing about it: you can make the game suitable for all ages.
I bet all those people who think otherwise (e.g. HP down to 10% the PC sure should miss a limb or two already) never argue when magical healing giving few HP, is applied, to interrupt the death saves and put the PC back into the game that the PC technically should not look much better than before.
Otoh roleplay it all you want, describe your grisly injuries etc. no problem with that, mortal combat can look like that, it just is not absolutely required to do that.