Well yes I guess all of that could be true if you ignore the fact that you only regain superiority dice back through resting for an hour or more(which in and of itself is enough to connect the maneuvers to some type of stamina expenditure)
I don't see how this changes the fact that whether or not this increases verisimilitude, or goes beyond mere metagame/gameplay considerations.
Encounter powers in 4e are regained only through
resting for five minutes or more. So they can also be rendered in the fiction as related to stamina and the like, by those who want to. (And the 4e PHB says stuff along these lines.)
Some people, though - as expressed in various posts over the years - think it is weird that my stamina to do Sweeping Blows is all used up, but my stamina to do (say) Passing Attacks is still all there. Hence they find the stamina idea, as an in-fiction explanation, implausible.
My point was that the same sort of concern applies to superiority dice. I can have all my superiority dice used up - so my stamina for combat manoeuvres is gone - but still have an action surge left, be at full hit points, be suffering no exhaustion effects, etc. Just like 4e, someone might see it as very "silo-ed" stamina, perhaps implausibly so.
This is why, in both systems, I'm inclined to see the mechanics as gameplay devices, and to not put very much weight on the stamina idea.
A lot of mechanics are pretty obviously metagame, and yet simultaneously induce verisimilitude (for many, this occurs upon reading of the rule, or at the very least during gameplay). The choice of a pool of uses vs a pool of one-use-each abilties may reflect the designer's intent to account for both goals for the mindset of the target consumer.
Sure. Presumably there are some people who find a pool of superiority stamina that is silo-ed off from the pool of hit point stamina, the pool of action surge stamina, the pool of exhaustion stamina, etc, more verisimilitudinous than silo-ing a pool of Disarm stamina from a pool of Feint stamina from a pool of Trip stamina.
Personally I'm not such a person, but that's why I said it's a matter of degree. Different people draw the line in different places.