Folks getting mad about whiteboard interviews is a meme at this point. It misses the point. We CANT test you effectively on your programming skillbase. So we test on a more relevant job skill, like can you have a real conversation (with a whiteboard to help) about how to solve the problem.
It isn't that your interviewer knew all the languages, but that the language didn't matter.
I didn't get this until I was giving interviews. The instructions on how to give them are pretty clear. The goal isn't to "solve the puzzle" but instead to demonstrate you can reason about it effectively, communicate your knowledge and communicate as part of problem solving.
I know many interviewers also didn't get it, and it became just "do you know the trick to my puzzle". That pattern of failure is a good reason to deprecate white board interviews, not "I don't write on a whiteboard when i program in real life".