On the flip side, how many of us have used horses for cow work that barely acknowledged the existence of cattle?
I know I sure have. Ponies like that were more reliant on the riders cues to get where they needed to be, but they were still good for the work.
So, I guess to me it doesn't really matter if the horse has "natural" ability. Unless they have some conformational problem that interferes with what they need to do, we going to do it.
I have a friend in his late 70s that started team roping a few years ago. One of his favorite horses is like that. They'd finish a run and I've heard the owner say, "He never even saw the steer." Or "Good job hoss, that was a cow in there."