I interviewed at Facebook using C++ and didn't have any issues. I guess maybe you were just unlucky. There are thousands of interviews so it happens that some are bad and you might get them.

And if you think C++ is too verbose I guess you've never interviewed in Java?

Personally when I interview people I don't care about specific syntax details. I do have at least a passing familiarity with 99% of common languages though, I think only once (out of ~500 interviews) did someone use something I had never seen before.