I've used both Windows and Mac computers. I thus do not comply with your sentiments. There are certainly differences, and certainly differences in what the user can see, but as far as knowing what, where, and how something works? Honestly, anyone sharp enough to even understand basic principles of using an OS, or processes which a computer is performing, should not be too different from the next guy in the room. Quite frankly, I prefer not to use a DOS operating system to get work done.
Mind you, above using software or managing processes, any additional knowledge usually falls into the realms of computer science, which is well and beyond most users, regardless of the operating system they employ. If you really want to complain about "dumbing down" technology, seriously, reverting to DOS is a great idea. Most UI's in a computer today are focused on actually allowing the user to intuitively navigate the software, which is ironically quite sensible. However, command line options never hurt anyone, either. But then, how often do you use those (this is of course not to say that you shouldn't have those options)?