I do want to stress the useless part here too- even with the notes of how the interview went I wouldn't be able to make a decision on things, since they didn't hit the points that were actually relevant to the role.
(EDIT: Note that I previously contracted with Karat and feel loyalty to them, but have no formal association or stake in them, nor do I represent them.)
What a contrast this is.
Karat is probably the best/fairest you can do for purely algorithmic interviews, but I'm not sure they're even able to do anything else (the parent commenter's experience suggests not).
I would also consider it more of an exam than an interview - the process is very standardized and sterile, and obviously since it's being outsourced there is no way for the candidate to ask any questions about the company.
(disclaimer as well: went into the interviewer onboarding with them as a contractor but dropped out as I wasn't comfortable proctoring tests that I myself wasn't an expert at).
I'm curious why you're so intense about this- do you have some sort of stake in karet?
Communication is hard, and not everyone has time or energy to bridge the gap, which is fair! It's just a bummer to hear that this has somehow lead to words like "awful", "real negative impact", "useless". That feels very intense to me, and I have probably responded in an intense way as well. There was no harm intended
We had a few months of really painful full interview loops with candidates not appropriate for the positions.
Literally all of our feedback was completely ignored. They didn't touch on any of the topics they said they would, and even though we explicitly told them it wasn't an algorithms heavy position that was their entire focus. On the plus side I did pass the interview, but we ultimately decided that using Karat would have had a real negative impact on our hiring.