We’ve written about how some people online aren’t interested in legitimate debates (no matter what they claim) and instead simply want to vent and unleash on others as a means of shutting them down. There are numerous ways to try to take away another’s voice, varying from direct and aggressive to more subtle and indirect means.
One typical way to prevent others from freely expressing themselves is through threadjacking.
Threadjacking, frequently used in online forums, mailing lists and chat rooms, is the “deliberate attempt at steering a discussion away from the original topic by bringing up another, which may or may not be relevant to the content of original post” and is often used as “a form of cheap amusement for trolls.”
(Image from knowyourmeme.com)