But why not? I already acknowledged that these situations are thematically muddy, because it confuses the question of exactly who or what the player is controlling. But I don’t see them as inherently problematic from a game mechanics design point of view. Do you?
Imagine that Gloomhaven’s ambiguity rule for monster attack targeting was replaced with “At any time as a free action, a hero may bang their weapons together and yell 'hey ugly, come and get me!` Any time a monster is deciding between two equally valid targets for an attack, it targets the hero that has done this most recently.” Same mechanic, conceptualized with different flavoring: Would you still consider this problematic “playing on the AI’s behalf”?
Equivalently, what if a wargame said “The player controls the Allied forces, plus one double-agent German intel officer who subtly sabotages their decision-making process from time to time.”?
A bit clunky conceptually sure, but I don’t see it as an inherently illegitimate way to design game mechanics. And I’d be intrigued to play a game that leaned into this sort of thing and took it even further, and said, for example, that every turn the enemy forces draw three possible action cards that are bad for the player in distinct ways, and the player chooses which one they will execute. Conceptualize it however you like (information warfare, traitor in their midst, bureaucratic incompetence, etc.), but I think there could be some interesting decisions for the player to make there.
In a recent game of Marvel United, on the villain’s turn, the action card says that they move to the nearest hero, attack, and spawn two thugs. Ant-man is two spaces clockwise, and Hulk is two spaces counterclockwise. Do I play it safe and send the villain to Ant-man, who has shrunk and is immune to damage? On the other hand, Hulk would be really hurt, but could retaliate by smashing all thugs at the location which would let us complete a mission. And what’s in the other locations nearby where the villain might move next turn? The right answer is non-obvious and requires thinking through what might happen.
Sure the game could have included exhaustive tiebreaker mechanics here, but in this case it would have robbed me of an interesting decision to make, so I’m not willing to call that a categorically better design.
I guess what I’m getting at is that every game consists of periods where the game mechanics dictate what happens, punctuated by moments where the player can make a decision. In evaluating a game, I want all of those decision points to be characterized by unity of purpose (at each one my end goal is the same). However, I’m not particularly hung up on unity of identity (it “makes sense” for the person or group that I’m nominally controlling to be making that decision). And even less so for unity of simulation (that whoever is doing the action does so in a way that matches what their historical counterpart would have done).