I can see your point (particularly with regard to deliverables), but I suspect the practice is quite widespread - comments often end up being used as a sort of brain dump.
That's a fair enough point, especially when directly employed working on closed source / proprietary code. You're essentially stuck in an echo chamber, and professional standards are more difficult to maintain when you don't have the whole of the world looking on.
I also imagine that the mental strain of figuring out edge cases and poor documentation in a system as complex as a windows OS would be enough to make anyone at least a little salty.
However widespread it may be, that does not me that I have to like it :D
For instance, see this article (from 2004) on comments in the Win2k source code: http://atdt.freeshell.org/k5/story_2004_2_15_71552_7795.html