The point is more that for a person with a given skill level, interviews can be stressful and make them perform below that skill level. I try to structure my interviews such that people get more comfortable and I don't ram their head into a metaphorical wall. I get all the same information, but without all those hard feelings.

The pressure of judgement is not the same as the work pressure of a stressful scenario. It's why public speaking and job interviews are among the most feared activities people go through, but people consider meetings boring and mundane.