Hitpoints are absolutely dissociated. They have no defined meaning in the game rules, they just abalate with no fiction attached to them. You can describe hitpoint loss in 100's of different ways, and they all are equally valid. I've even described them as completely dissociated in a plot coupon manner, and they still work exactly the same way. You are confusing your habitual gloss on hitpoints with how they actually function.
Armor class is the same way. If I fail to roll a success on my attack, what happened? Doesn't matter to the game, it can be anything the players want to describe. You can even do the same treatment I do with hitpoints and invoke armor class as plot coupon to force a miss.
And spells, oh, those lovely spells. These are exactly what you claim to hate. Take the secret door example, where you're absolutely against any concept where players searching for a door causes a door to exist. Totally bogus, right? You're even against the players spending a plot coupon to say a secret door is here -- dissociative! Do not like! But, you're absolutely perfectly fine with a player spending a plot coupon to open a door on command, so long as that plot coupon is a "spell slot" and it's used on "passwall" (I believe you're an older edition player, so this is still a spell for you). This does exactly, exactly, the thing you dislike, but it's okay, because it's lampshaded behind magic and you're used to plot coupons as spells.
And, to get in before the inevitable, this isn't dismissive, it's stripped -- stripped of the patina of long familiarity and cast in a stark light where these things can't hide in the shadows of what we're used to.