I've had some surprisingly good feedback experiences in recent interviews.

One was at a 40,000-employee global tech professional services firm. I got feedback from each interviewer filtered through the recruiter at each step along the way, sharing both positive and negative. This process ended in an offer I didn't accept.

Another recent interview process at a FAANG ended in a rejection. The recruiter followed up with me and informed me which interviews were considered a pass and which were a fail. Each interview had several components, and the recruiter was able to tell me which components were the cause of failure in the one interview, and what to focus on in any future applications to the company.

I presume it's a liability thing. It only takes one candidate to "spin" an otherwise valid reason into something they can sue for. Same reason why companies don't tell employees what they're being let go for in at-will states.