If there is a big company that hires a lot of people and this is managed by many HR stuff, it is much cheaper and safer not to give any response than go through every rejection response to double check if something seemingly innocent cannot be interpreted as "discriminatory practice", rightly or not.

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.

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.