Slashdotting

Well for it to be a crime there must be a law against it. Some countries don't have laws about it, meaning some places on earth don't consider DDOS a crime.

This is why I asked the question, as the grandparent poster seemed to be making some sort of legal or moral point conflating a DDOS with the right of assembly. Nonetheless, strictly speaking there are clearly many forms of DDOS that are not illegal (DDOSing your own equipment, for example, and those situations you explain) but they don't seem to fit well into the point he/she was trying to make.