I call BS on the interviewer because as this thread and that question I linked on Stack Overflow demonstrates, "joint table" is not "the" term for the concept in question, and in fact there is no accepted one term. So, "marking down" for not knowing that term doesn't seem right.

Edit: On the other hand, asking the question in a way that gets at the concept, not the term, seems very reasonable.

I don't think it's relevant, but yes, I have interviewed at such companies.