It actually started on 4chan some years ago. Originally it was used only to mock a specific type of person, but then as time went on more and more newfags started overusing the word, and basically using it as a crutch. Then of course redditors started using it to describe anyone that wasn't an SJW and the word completely lost all meaning.
The same exact thing happened with the whole "fedora" meme. I'm not sure if 4chan technically started that meme, but it was originally popularized on there at least. And again, it was originally using to mock a specific type of person, but people just started posting "*tips fedora" at anyone they disagreed with (or just as a means of shit posting) and then reddit and tumblr got to it and managed to ruin it even further. The ironic thing is that the type of people constantly using that meme these days are the EXACT kinds of people the meme was originally intended to mock....white knight male feminists looking for an excuse to defend m'lady.