As well as the annoyances you point out, there are also the people who haven't a clue but decide to weigh in with their half-baked opinion anyway.

This seems especially prevalent on the Apple forums. I've lost count of the number of times I've seen some poor sod advised by some 'know nothing know-all' that the answer to his/her problem is to "reinstall MacOS" when their issue could easily be solved in seconds by deleting a corrupt preference file, or fixing an incorrect permission.