Agree that it depends, but, like I said, most stuff would be pretty easy to trace. One would need to be very proactive about choosing to try to hide their tracks for posting.

And just posting from an "anonymous" IP may not be enough, depending on other browsing habits. With things like tracking cookies and such someone could do a decent job of assembling a historical pattern and probably not struggle too much to actually figure out who someone is.

Anonymity on the internet is, for the most part, rather difficult to maintain.