Once upon a time there were generally understood rules of social conduct (see: Miss Manners, Dear Abby, et al) whereby people could largely get along with each other.
Over time these rules grew to be regarded as antiquated and sexist, and people grew increasingly daring with speaking their minds and challenging social norms (see: Elvis, Beatles, punk).
But then people began to feel uneasy with such outspokenness as various groups (from gays to Baptists) demanded to be taken seriously and treated with respect.
As these demands for more stringent and "sensitive" political correctness began to feel smothering, people sought outlets of escape (see: 4chan).
In time, once again, the novelty of being able to say almost anything wore thin as people went beyond merely saying whatever outrageous things they liked to trying to be as offensive as possible. At some point a tv show came along and reminded us what it's like to not be constant assholes to each other, and at least some part of the world population embraced that.
But then the show started to suck and even those who regaled in this show slid back into their outdated ways. And here we are, factions of the politically correct and the trolls still at odds while our own segment wavers uncertainly between the two.
This is of course grossly oversimplified, and I'm sure there's more to the history prior to where I started, but you get the idea. This shit's been going back and forth constantly for decades. For my own part, I'm content with being able to speak my mind when I feel it's worth saying, while trying not to be a dick in the process.