So you can't point to any art or trope in D&D that suggests that mental stats are irrelevant to how well a fighter fights?
You can't point to any examples of the "dumb fighter" who would be invalidated by allowing those stats to have additional interactions in combat.
Your whole reasoning is "not wanting nerdy-looking kids to fight like badasses (unless they select an appropriate casting subclass)".
Cool..seems like a solid argument.
Versus what? What trope or examples can you point to that shows intelligence allowing someone to win based on physical combat alone? Excluding Sherlock Holmes?
Martial arts? Sure. That's covered by the monk. Dexterity based? Sure. Intelligence? Those are all going to be wizards or rely on technology. As far as additional? I guess I wouldn't mind some additional benefit but that's not what's being discussed. I'm talking about the wimpy, clumsy, but intelligent person winning a fight using swords, fists, bows or other non-technical weaponry.
Virtually every example we have of a fighter is either the big brawny guy or someone using dexterity to dodge out of the way while getting past the enemy's guard. I don't have to prove anything - there are a ton of examples of those types of fighters. You're the one trying to create a trope that simply doesn't exist.