The requirements to open yourself up to a discrimination lawsuit are fairly high.
Legal doesn't have 'interview experience - net promoter score' or any other interview quality metrics as one of their KPIs, so they're happy to mandate the nuclear option because it gets work off their plate.
It's less about what the laws say and more about what the consequences of not following industry standard would be.
If you explicitly flout standard and as a result get sued for violating one of the related hiring/discrimination laws, your investors may have a good case to sue you personally because you didn't act in the best interest of the company by opening your company up to that extra risk for no tangible benefit.
Legal doesn't have 'interview experience - net promoter score' or any other interview quality metrics as one of their KPIs, so they're happy to mandate the nuclear option because it gets work off their plate.