It does have virtues and flaws, however, which can still force players to play their characters in ways they wouldn't, which was my point. "Only the player should decide how their character decides things" is a position any number of games do not share in various places; they aren't usually about attributes, but they're still things that can entirely be cases where the GM, the mechanics, or both are overriding the player. So if you want to say that this sort of thing is entirely off the table, you have to limit that argument to some games, or make an argument why a low mental attirbute is intrinsically different from a psychological disadvantage or the like.