> They also assume collaborative interviewer, which has never happened in my experience.

As a FAANG interviewer myself, this is very sad to me. System design interviews are inherently collaborative and they can provide a pretty good signal on "do I want to work with this person". I thoroughly enjoy conducting system design interviews -- It's always a joy to talk through the problem with the candidate and sometimes I even get to learn something new myself!

We really need to fix the tech interviews.