I'm drawing a fine line and doing a bad job of it. I think feedback is good, but I don't want to overvalue the feedback from the interviewer. That message is

I'm drawing a fine line and doing a bad job of it. I think feedback is good, but I don't want to overvalue the feedback from the interviewer. That message is going to be specific to that hiring manager and organization, and some stuff might be made up because it's safer to say you did poorly on the whiteboard coding than it is to say you weren't a cultural fit. So even if you get feedback there, it may be to backfill the reason for not hiring you that they might not actually want to share. Objective eyes are good. Do the exercise with someone disinterested and see what they say. It's not that feedback isn't valuable, it's that the value from the interviewer is limited for the reasons above.