Well you got the definition wrong so no wonder you can't figure things out. You most especially got the bolded part wrong. While true that it could effect some people that way the word dissociation is not referring to a feeling or experience while using the mechanic.
I'm still confused: is feeling important to the notion of dissocatied mechanics, or isn't it?You ever ask yourself why half the playerbase went to Pathfinder? My guess is healing and dissociative mechanics (though the term DS wouldn't have been used the rejection of the feel would be there).
I view hit points as overal health and vitality both of which are known.
A player in D&D often knows that his/her PC has enough hit points remaining that s/he cannot die to a single arrow, or cannot die from jumping over a 40' cliff. This is possible even for a character of modest level. (Eg a 2nd level fighter can have enough hit points to be immune to death from a single arror, and by 4th level will typically have enough hp to be immuned to death from a 40' fall.)I never heard anyone ever think differently until I went online. I probably know a hundred people that think their characters know their hit points. I know that is anecdotal but I just never met any resistance on that. The point though is that if I thought hit points were completely unknowable then I would be opposed to them and probably just quit D&D altogether.
No human being in the world can now these things of him-/herself.
Hence I have never met anyone, until I came online, who thought that hp corresponded to PC self-knowledge. They are information for the player about the buffer of luck/plot protection that the PC has. (Much as Gygax described in his DMG.) And for those players who didn't want to play a game with this sort of mechanic - and I've known plenty and been one from time-to-time - we played RQ or Rolemaster rather than D&D.
And flipping it around - if a PC in your gameworld can know that s/he is lucky enough to survive an arrow shot or a 40' fall with absolute certainty, then s/he can know that s/he is lucky enough to pull off one clever move in the next 5 minutes, but no more. (Ie there is nothing inherent to hp that makes them playable as non-metagame that is missing from 4e's mechanics.)
There is a perfectly good non-pejorative word for mechanics that do not correspond to a choice the character makes in the gameworld: metagame mechanics.Mechanics which force you to leave actor stance and enter author or director stance are dissociative because they dissociative the character from the player. When the player is making a metagame decision, he is not "being his character".
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It's been explained a million times so I can only guess this answer doesn't fit your mental model so you ignore it.
And the claim that a player cannot use metagame mechanics while being in character is an empirical claim that is false: for some counter-examples (and many others could be given), I refer you to posts 477 and 498 in this thread, and the ensuing discusion.
In other words, my mental model is fine. I understand what you're saying - I'm just denying it. If you want to necro the thread I've linked to and discuss it further, I'm happy to.