Hard to overstate how important this is. Hiring by skill and ability in itself is prohibited because every measure of those demonstrates that they're unequally distributed across groups. "You just have to make a non-discriminatory test of ability" is required and impossible
Hard to substitute tests and verbal stuff for non-verbal evaluations in a business where the hands on managers are all going to be men who favor action and aren't the type to articulate exactly why they come to the evaluations they do - have to be able to fire for "no reason"