You have to also consider selection bias. YouTube has a lowest common denominator appeal. And the stuff you're talking about primarily appears on things that are even further lowest common denominator appeal. You're not going to find people ranting and raving on the comments to something like a Leonard Susskind lecture on YouTube.
Take the other side of the issue. Anonymity means people can discuss controversial views without concern for what other people might think of them for holding such views. So for instance, consider Nazi Germany. The Nazis were never actually particularly popular in Germany [1] but managed to obtain a stranglehold in power largely because they made people afraid to say otherwise. It was difficult for people to speak against the Nazi party when all it took was saying such things to the wrong person to end up getting 'disappeared.' Without the ability to completely suppress free speech, the Nazis likely would not have managed to obtain power - and certainly not to maintain it.
And the above is something that is a constantly recurring theme in history. Those that would do bad things enable their actions by making people scared or otherwise unable to speak against said actions. This should sound familiar given recent events. It's increasingly seeming that sexual abuse is something that is completely systemic in Hollywood. But the powers that be were protected by the fact that their victims were unable to speak out. For instance Weinstein managed to kill a New York Times article that was being written about his abuse, 13 years ago. And in the past accusers of people like him would be putting much more than "just" their livelihood in jeopardy. But the internet allows these people to come together, have a much larger voice, and indirectly protect themselves and also substantiate their claims. A few isolated claims can be explained away - dozens, if not hundreds, of claims cannot.
I would argue that what we're seeing is an evolution of society, with some growing pains. Ultimately being upset about what somebody says on the internet is pretty pointless. I mean really we all should be seeing things that we disagree with, fundamentally and vehemently. If people were honest in real life - this would also be the case. I do not think that people censoring themselves, or making themselves somebody they are not, for the sake of social conformity is a positive trait. Yes it spares peoples feelings and helps things get along, but a social consensus (which defines our state of society) built on falsehoods and invisible pressure is no consensus at all. The reason the civil rights movement succeeded is because it happened long before the civil rights movement, as we know it, actually happened. The masses had long since changed their views, but social pressures prevented discussion of such.
[1] - https://news.ycombinator.com/item?id=15841818