It could be that this phenomenon has arisen, at least in part, because people need to feel better about themselves. Now, of course, we all need to feel better about ourselves. Certainly, most of us want to, I think. But, imagine if that need became a neurosis, in essence, a demand that everyone and everything must – indeed, is obligated – to make them feel better about themselves. And certainly to never make them feel bad about, or even doubt, themselves.* These things are discouraged to the point that individuals and groups will, apparently, not pause to think twice about crushing anyone who behaves otherwise.
If you combine this supposition – which, as a scientific idea, is actually testable and falsifiable, and so qualifies as an hypothesis (though testing it would be difficult) – with access to the internet, you get a situation identical to the one facing us. In fact, I would think if my supposition is flawed, it is flawed primarily in that it has downplayed the hand-in-hand evolution of the internet and this sort of privileged/entitled demand that "my" self-esteem be placed before all other considerations. Never before have such a mass of people been able to behave this way, with a willing audience, worldwide, at the speed of light.
* It seems to me ironic that these same people often air the most minute and private aspects of their lives in public, as though daring anyone to speak ill, purposefully or accidentally. In effect, these people sacrifice privacy as a means to gain potential outrage.