I think it'd be really fucking impressive if someone could discuss the ins and outs of systems they've used, likes and dislikes, taking conversational questions

I think it'd be really fucking impressive if someone could discuss the ins and outs of systems they've used, likes and dislikes, taking conversational questions about it that they don't know about in advance, without setting off any alarms, while not actually knowing anything. That'd be wild. I think a lot of the whiteboarding/leetcode stuff is just hazing, a desire for "standard" processes (every candidate has a different background, so a well-done conversational interview will differ a ton per-candidate), as a bit of a time-filler ("that's right [C-suite person who's asking questions] we have very rigorous hiring, look, it takes six hours, and see all these steps! Only getting the best of the best, I assure you."), and because if it's scripted you can have mid-level devs do it—poorly, for the most part, since conducting a good whiteboard/leetcode interview is possible, so far as that goes, but it's not easy and requires serious people skills, which is a big part of where places go wrong I think, and also tends to make it look so non-cookie-cutter that if you squint it's not really that much more "standardized" than the conversational version.