The problem is that resumes can be deceiving. If you've worked long enough in the industry, you've met a few incompetent people with stellar resumes. It's why having google on your resume opens a lot of doors. Everyone respects google's vetting/interviewing system.

Also, fizzbuzz isn't anything you really need to study for (certainly not for days or weeks). It's something you should be able to work out during the interview if you truly have developing experience. But then again, I've known people with amazing resumes who couldn't even understand the fizzbuzz question itself.