There's a difference between rude and illegal. I think the original commenter was speaking more about illegal behavior leading to accidents.

In my experience in cities where cycling is built into the architecture of the city, most do tend to follow the road rules. However, a pedestrian might still find it rude if a cyclist were to pass close enough to brush shoulders, or a driver might find it rude for a cyclist to lane split.

From my perspective that kind of "rudeness" is just part city life, though, it's not really something exclusive to cyclists.