During combat, participants make decisions for the characters they are controlling which matter to how things turn out (eg decisions to move, to cast healing spells, etc) and which are chosen based on knowledge of the mechanical state of the game (eg where another character is on the grid; what a character's current hit point total is; etc). But at least some of the fiction that corresponds to those mechanical states can't be known until after the decisions that matter have been taken and the actions resolved. Because only after the event do you get the sort of "emergent" fictions that you are putting forward.
It might help to look at when decisions are being called for. Under my approach (T is for time, not turn) -
T1 =
DM: based on how things have unfolded, let's roll initiative
T2 =
Fighter Player: rolls lower than DM
T3 =
DM: decides what orcs do, and resolves their turns
T4 =
Fighter Player: decides what they do, based on the current game state (groans weakly, dying)
T5 =
Healer Player: decides what they do, based on seeing the current game state (fighter groaning weakly, dying): casts
It sounds like you might be describing -
T1 =
Fighter Player: decides what they want to do
T1' =
Healer Player: decides what they want to do
T1" =
DM: decides what orcs will do
T2 =
DM: based on how things have unfolded, let's roll initiative
T3 =
DM: because orcs won initiative, game state is unchanged so unproblematically resolves what they decided to do
T4 =
Fighter Player: what they decided to do is now at odds with the current game state: insert sound of SoD shattering
T5 =
Healer Player: didn't decide to cast healing because no one needed healing back when they decided: sound of SoD shattering intensifies
Can you correct the above, which I feel sure I must have laid out wrongly?!
This means that those decisions, and the knowledge they are based on, don't themselves correspond to decisions being made, and knowledge possessed, by the character whose action is being chosen by the participant. In that particular sense, D&D combat is fictionless - ie it involves purely mechanically-driven decision-making that (from FrogReaver's point of view) "masquerades" as in-character/in-fiction decision-making.
One nettle I am grasping is captured in that word "
masquerade". I say that "
Yes, it truly is all a big masquerade!" For the purposes of play, if the pretence is good enough, then it
really is good enough. It matters how hard you look at it; what subjective hoops you make it jump through.