I'm not sure what it is like in Sydney but in Melbourne the bouldering community has exploded in the last 5-8years. In many ways this is a good thing. But it also means more people with less knowledge of what is and is not appropriate in climbing and the outdoors in general.
It is sad, but hopefully the bouldering and climbing community can all do their bit in ensuring that appropriate behavior in our beautiful outdoor areas is maintained.
I haven't been to some of the grotty European sport crags but from the stories I've heard it isn't a path that I'd like to our crags go down.