The thing is, if someone is doing it to you then yeah, its fine to do it back to them but it sounds like you are butthurt your NMs got stolen so instead of paying it back to the group that did it to you, you do it to other people that did you no wrong at all.

If you are camping people and doing it over and over again, you are griefing. Not really wise to admit that on the official forum, lol.