That experiment assumes that SWE job is exclusively about solving technical problems, so we can just "lock the candidate in a private room and let them solve it". In reality human to human interactions, sometimes stressful, are part of the job. Customer & PM requirements, technical debates, giving feedback, explaining your technical solutions, etc. are common. Maybe part of the problem is the education that does not…
But if I'm interviewing you for a senior SQL engineer position, and you can't talk me through whiteboarding a simple query with one join and one aggregate function... you're not senior material. I'm sorry. We need people that can communicate and explain themselves, and talk through their own line of reasoning, where I work.
Again, I'm not defending SWE interviews... but of course people are better at expressing their skillset when they're in a controlled environment. The trouble is, the workplace isn't a controlled environment. Life isn't a controlled environment.
I don't want to work with brilliant programmers that have zero social skills. If devs can't muster up the courage to answer interview questions... maybe that means that they should work on themselves a little bit?