This doesn't represent the argument of your opposition in this thread. The argument actually being made neither completely nor even partially discounts character generation as meaningful declaration by the player.
With respect to what you've written above, the argument being made states:
1) Ability score (modifier...which is what is relevant unless we're talking AD&D NWPs and rolling under score) is only one input to the player's process of determining action declarations at the table.
2) Ability score (modifier...which is what is relevant unless we're talking AD&D NWPs and rolling under score) is only one input to action resolution.
3) In systems that have a multitude of PC build components, PC flags, reward cycles (which may incentivize action declarations which end in complications or player intent unrealized...such as Inspiration for a Flaw in 5e or xp in Burning Wheel and Powered By the Apocalypse systems), specific play agendas (push play toward conflict, test your beliefs, play to find out what happens), and GMing techniques (such as Fail Forward), there will be several other inputs that can serve as the primary signal for how play outcomes are realized at the table (the totality of which generate archetype, genre coherence, and story).
4) The fickleness of Social Contract (not intra-table, but across the spectrum of TTRPG tables) is not insignificant. This is on display in every thread ever posted in the history of RPG forums.