Rather begs the question why such libs don't have such helper functions as blitz, doesn't it? :)
It's not the having them that's the issue - many do have them - it's the *only* having them that's the problem. You can't use Quaternions or Matrices with Blitz3D even if you know how to. These days, games are not being programmed in C++, they're programmed in Lua or Python. So if you're after a job that requires C++, you're after a low-level job, engine programmer or at least expected to work with the engine at a low level, in which case you may well be the guy who's required to *write* those helper functions, not use them.