4e uses (I think) 3 "dimensions" of quasi-tangibles.if HP really are suppose to represent all those quasi-tangibles of the target (perserverance, skill, endurance, etc.) that go into keeping the target in the fight, then an effect should not be able to sidestep those HP any more than an arrow or swordblow should be able to decapitate or KO the target in the middle of the fight.
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The difference between paralyzing an enemy with 20 HP or pushing him 2 squares is a matter of degree, not quality. But that leaves you with a pretty straight-up ToTM attrition game that isn't very exciting at table for tactically minded players (I would think).
There is the "hit point" dimension, which is related to resolve, luck, endurance etc.
There is the "debuff" dimension (eg being dazed, slowed, -2 to all defences, etc) which basically occupies the same space in the fiction but via a different mechanical framework - primarily but not only toying with the action economy. In a typical skill challenge, which doesn't work with the same degree of detail, all this stuff disappears and is replaced by simple hp/healing surge depletion.
I think the reason for having this stuff in the game as mechanically distinct from hit points is the tactical fun reason that you canvass. I think the reason for making it mostly light touch (at least by D&D's traditional save-or-die standards) is to stop it from overwhelming the hit point dimension that is mechanically distinct but occupying the same space in the fiction.
The third dimension for 4e is positioning (including shift vs walk, prone vs standing, force movement and teleportation, immobilised, etc). This occupies a different space in the fiction (although in some cases one might imagine a degree of overlap - the combat advantage granted for being prone, for instance, looks like a type of debuff that could equally be represented by hit point loss that correlates to a character being put in a disadvantageous position). It is the closest 4e combat gets to simulationist resolution.
In my own experience, the existence of these three dimensions, all of which somewhat overlap and two of which highly overlap as far as the fiction is concerned, is not an impediment to "immersion" and a sense of how things are for the PCs in the fiction. Getting rid of them all would seem to require a move to abstract positioning and much more simple action economy - both big moves for D&D. (I'm thinking of something like Marvel Heroic RP. Does Dungeon World simplify in this sort of way also? TotM, at least in the traditional D&D approach, is not abstract positioning but just approximative concrete positioning.)