It's not about the system working or not, it's more about whether it's well calibrated. You'd expect performance to scale linearly with skill (f(skill) = job_quality * x), but the data look more like a sigmoid: overqualified people disengage and never hit their full potential. Underqualified folks aren't that far behind their peers, yet in a better-matched role, they'd perform better with less effort.

I find it kinda sad, honestly. But these are aggregated statistics, I still think people can overcome their perceived limitations, I'm certain some of the underqualified folks are the ones that drag that curve up a lot.