It's actually simple. If you don't have time for
its wiki article, I'll give you the quick-and-dirty:
A bunch of entitled fucking idiots invaded a hobby they had no stake in and tried to bring a culture war with them. During this, one of their darlings got their sexual indiscretions exposed, and when the indie journo circuit tried to close ranks to protect one of their own, they got exposed as not only being in collusion but financially supporting the indie darling in question. The brainlets in the indie journo circuit doubled down once more, attacking their own audience and declaring that gaming hobbyists were over and should no longer be appealed to by developers, instead embracing identity politics. The gamer nerds in turn responded by calling out their shit, getting the FTC involved, conducting many boycotts, supporting numerous charity drives, and exposing many other examples of journalistic fraud and malfeasance. Enraged with their enemies getting the better of them, the indie journo circuit decided to push the narrative that allowing any discussion of GG
at all was tantamount to enabling the harassment of women, evidence be damned.
Despite the full support of the indie and mainstream press, the indie journo circuit ultimately failed to stop GG in any meaningful capacity, and while they arguably won the PR war, the Autists won every other front. The hashtag wrapped up in October of 2015 after Zoe Quinn and Anita Sarkeesian's disastrous UN appearance obliterated any credibility they may have had.
TL;DR: Great example of Gaben's Law and the Streisand Effect.