I've said this on StackOverflow, SuperUser, and everywhere anyone has ever mentioned anything like a [beginner] tag. Tags like [beginner] and [fundamentals] have two problems - they are not well-defined nor do they have a strong meaning to describe the content.

What is a fundamental or beginner concept to you might be second nature to me. Let's take the recurring theme of a system administrator with 15 years of experience in Linux- and Unix-based systems. This admin takes over a Windows system. He is not a beginner, nor does he know what the fundamentals of running a Windows system are. He does, however, understand key words such as "batch script", "service", and "shell" and can use these key words to tag his question in meaningful ways.

Even if the tags weren't applied by the asker, you still have the problem of defining what is fundamental or beginner - not everyone draws the lines in the same place. And it's harder to define skill levels than it is key words (especially technical words).

All of that said, however, a methodology for defining things like "beginner", "intermediate", "advanced", "fundamentals", and other similar words would be of benefit to every Stack Exchange community. The specifics would have to be done by every community, but a process that has worked once and can be applied multiple times would be useful in developing communities to be able to categorize questions.