Could someone enlighten me what the problem is with automated documentation systems?

Have they stopped to "just work" in creating an overview of all global variables, functions, classes and their inheritance?

I found it very convenient to just drop a few documentation strings at the function/class definition for looking it up later in the autogenerated documentation. Of course you can overcomplicate these things and waste time. But in my opinion autogenerated documentation is better than no documentation at all.