1. It is the result of the self esteem movement reaching its full zenith. If the most important thing is that you feel good regardless of performance, no one is allowed to say anything that hurts your feelings - even if it is true, even if it is not intended to offend.
2. It has been said liberal morality is do what you feel while conservatives are do your duty. Liberals have gone so far to say that if you feel like a woman, you are, even if your feelings can change next week (gender-fluid) or attributed to mental illness (dysphoria). If you feel someone's motivation is hate for disagreeing with you (psychologists call this mind reading), you label the speech as hate speech and demand it is banned. It is censorship by way of feelings or simply pretending to be upset, and people will abuse such power when you give it to them. Just look at HOAs, and give the same nazi types permission to censor day to day discussions.
3. You get permission to be a bully or violent if it is in the name of protecting a politically correct class. In the case of my son's religious school, these people cloaked in peace, love and tolerance threatened to burn it down with the kids inside. The religious school said we don't accept the children of LBGTA because we teach traditional marriage in class and in mass. We don't want to send kids home saying Mommy, other Mommy, you're a sinner. And we don't want to change our religious views - people pay to attend a school that reinforces their values. A Democrat county precinct chair and lesbian tried to enroll her child for kindergarten, refused to fill out all paperwork, then at the last minute when told we don't enroll children unless both parents agree to the theological section, said the other parent is another woman. The school gave her the deposit back and a list of public and private schools they could attend. They ran to the press and cried homophobic. That was all over the national media.
Then the hate mail came to the school, suspicious packages, death threats. That was NEVER reported outside the rare police blotter, like the attempted break in to the school. It lasted months. And the same pattern has been repeated at other religious schools.
Or the case of Christine Sacorro, one tweet taken wrong, and she loses her job, gets hate mobbed online. And the people who called for her to be raped, murdered, given AIDS were never criticized. There's a TED talk on that case.