Lots of truth there. I read somewhere that a good predictor of a person's ability at high-level manufacturing work is his/her score on a basic algebra test.
I certainly wouldn't use it as the only evaluation, but an algebra-based evaluation makes some sense to me. And it is something that you can improve upon with enough perseverance.
Perseverance counts for a lot. Someone who doesn't have much aptitude for such things but is willing to put in a lot of effort toward mastering them may accomplish far more would be predicted by an aptitude assessment, and efforts to assist them in their mastery of the subjects may be worthwhile. On the other hand, if someone lacks the aptitude to learn easily and the perseverance to push on anyway, there's no use trying to teach the subject unless or until their they get ability and desire to persevere.