Not always. How's the old saying go...Sometimes (in fact MOST times) it's just as easy (and better) to be the bigger man, shut your mouth and not reply to what you see as provocation.
"Say a lie enough times and it will be believed"
Sometimes not responding is just as bad. And when things are left unchecked for an extended period of time and repeated over and over... You either have to defend yourself or someone of authority needs to intervene. I was wrongfully denied both.