I've attended many trainings like this. They always talk about correlational studies as if they're causal. "More diverse teams make more profitable companies!" But in reality it's just as likely to be reverse causality. Companies that are very profitable have enough resources to be trying non-mission-critical things like diversity.

I assume that if there were better evidence out there it would be presented in these trainings. The fact that this is all that is ever presented indicates that there is not. It also indicates that the trainers are either unaware of the difference between correlation and causality, or they simply don't care.