Being a good developer requires the ability to write logical, maintainable code of course, but equally it also requires having the ability to talk to other developers, to work with a team, and to explain technical problems to non-technical people. Those are soft skills.

That's a non-credible excuse. If it's really about how you deal with adversarial situations, there's no reason for coding to be involved at all. There are plenty of other scenarios you could role-play that are more realistic and/or more informative wrt what software engineers actually do. Why don't people do those things instead? Generally, because it was never really about communication skills or reactions to stressful/adversarial situations. That's just the rationalization that people who actually did intend to measure coding skill come up with when they're forced to admit that the tool they've chosen is spectacularly ill suited to that purpose. Nobody wants to admit they've wasted so much of their own and others' time.

...and the rest of us are supposed to read his mind? Since we're talking about communication skills here, I submit that good communication skills might include stating one's meaning more clearly.

There's more to talent than writing code. It amazes me, this attitude that testing for social skills and fit is seen as insulting. Believe me, it's for the candidates benefit as much as the potential employer.

The original poster and you responded you do similar things. You meant something different I guess.

I agree very much with a coder is not supposed to only code; I guess we agree if you take away the specific 'I had to code on a whiteboard without even a computer present' of the OP.

But yes what you suggest here is what we do. And that is actually fun for the coder (if not highly anti social) as well as it is for the team too.