If the point is to "teach them a lesson", then the cause loses any pretense of moral high ground. All it shows is that if the positions were reversed, they would have acted in the same that they condemn now.
I think it comes down to the internet and media enabling fringe positions: the loudest, most extreme positions receive far more attention than they should and can gather an audience. Most people don't buy into the extremes and are fairly reasonable, but you won't hear about that. Instead you'll hear the left calling anyone opposing free-for-all immigration nazis and those on the right saying deport all foreigners.
All it shows is that if the positions were reversed, they would have acted in the same that they condemn now.
Two wrongs do not make a right (but 3 lefts do!) ? That sums up my position exactly. Thank you for putting it into better words than I could.
I also see the "pack mentality" of the social media and controlled forums like reddit and voat, where users can control the dialogue, and the majority becomes the rabid controllers of the content through their numbers, and the positions become an echo chamber of one side or the other. Then, the Overton window effect takes hold, and the "center" position moves just a bit right or left as the opposition side is reduced through attrition. Then, that extreme position moves a little closer to center. A few cycles of this, and that window shifts to where the extreme position isn't even extreme anymore, it's simply "left of center" for that particular site.
MSM, I beleive, has the same issue, where 80%+ is left of center, the window shifts so that even middle-right positions become radical rightwing positions, or in today's terminology, "alt-right." And the constant barrage of anti-Trump is alienating 40%+ of their watchers, as their worldview is so skewed due to the echo chamber of the vast majority position, that the Overton window has moved to the point where simply being a Republican is outside of it, so the mere concept of Trump is beyond their comprehension.
We have seen it occur on reddit, where just supporting Trump makes you a racist, xenophobic, Nazi, alt-right, piece of shit who is the scum of the earth, or on Voat where if you don't spew genocide as the one true position, you are communist "kike" shill.
There really isn't a good solution for this that I can see, the reddit "user controlled narrative" through up and down votes brought about a change to avoid the forum sliding that happened on the older boards (about.com, delphi.com, etc.) without paid moderators, and to put together a model that allowed for no paid moderators, but brought on a new issue of silencing the minority opinion. We know from the Greeks that pure democracy always degenerates into demagoguery and then majority tyranny and monarchy always degenerates into absolute power, so mod only and majority opinion both devolve. Combining them works, provided that the mod is of the minority thought, but then they will be run off by the majority, or they will start banning the majority, which kills the site. Not sure if there is a good solution, except to leave once the tipping point of censorship of THOUGHT (not abuse) is reached.
Some might say "Sucks, doesn't it? Now maybe you'll understand better what it's like to be black/gay/female/foreigner/etc." but I am not sure that's the best way to go about it. Seems a bit immature and vengeful way to go about making a point - it seems like the same kind of thinking that goes into riots that destroy one's own neighborhoods, the "Oh yeah? I'm pissed, so I am going to fuck up my shit worse. That will show them!" mentality doesn't make a lot of sense to me personally.