I dont think there is an level of disadvantage that can't be overcome with enough competence. If the disadvantage largely exceeds the competence then yes the naturally the competence makes up a smaller proportion of an individuals agency, but the opportunities still arise to take advantage of said small level of competence to SOME degree at least.

There are people whos disadvantages out way their competence but that doesn't mean they have no options at all. And id think its a very very small minority of people in the first place.