Especially when the argument is over something that is both important and where it isn't just a matter of subjective opinion and in fact is something rather important. Like, say, that the whitewashing of a movie set in an undeniably Asian fantasy world is unacceptable.
It's one thing to ask people to be civil (although even that tends to be pretty fucking condescending), it's another to insist that OH WE SHOULD ALL STAND TOGETHER AND HOLD HANDS AND SING KUM BAH YA, NOT FIGHT YOU SILLY-BILLIES
WE HAVE TO STAND TOGETHER OR ELSE WE'LL DOOM THE FRANCHISE! DOOOOOM IT!!1