As far as I can tell, the major offenses in Gamergate involved instances of sexism in the video game industry, in the media, and online, compounded by instances of intimidation and doxing. People who were paying attention to this among the liberal-left rightly concluded that this was gross and condemned it. Weird Twitter, which is so often on the right side of history, trolled these guys too - but this is where my perspective starts to diverge from a lot of liberals.
Here, my impression is that a lot of nerds like Arthur Chu and bourgeois liberals like Amanda Marcotte took the outpouring of support for the actual victims of Gamergate as some of kind popular endorsement of the whole of their own idiosyncratic and often ridiculous politics.
So for example, some guy made some cartoon about "sealioning", and some critic of Gamergate who goes by the name of Dragonmaw wrote some things about how sealioning is an "insiduous" "forced violation of empathy" that is "only one step removed from actual interrogation techniques". And then, insanely, the nerds and liberals who agreed that this was a serious problem concluded that everyone else thought this was a serious problem, too. Which means that today, we actually have guys who think that sealioning, by popular consensus, is some kind of deontological taboo that must be rejected even when it's indistinguishable from a sustained critique of drone strikes:
Just as they've invented mostly absurd theories of "sealioning" (old enough to remember when we just talked about "passive-aggression"), these people have also hijacked all kinds of legitimate concepts and critiques in some of the most ridiculous ways imaginable. For instance, gaslighting is generally recognized as a real psychosocial phenomena that typically occurs in cases of domestic abuse and clinical malpractice. This is not some incidental point of trivia about gaslighting; it's a significant prerequisite, because for gaslighting to actually take place, the target generally has to be in a psychologically intimate relationship with the gaslighter, and thoroughly immersed in their domination. Yet a whole genre of nerds and liberals now think they can be "gaslit" simply if someone disagrees with them:
This is an indefensible (and frankly disgusting) appropriation of a concept created to protect people who are subject to serious, often life-threatening abuse; and yet liberals and nerds not only invoke it, constantly, but seem to think there is some kind of popular mandate behind them.
You may have noticed a recurring theme in these examples: sealioning and gaslighting are both terms used to delegitimize criticism. This, in practice, is the raison d'etre for this whole genre of politics: its idiosyncratic and half-baked narratives are consistently (and often blatantly) centered around building a defensive wall against criticism or dissent of any kind.
So it's easy to see how the politics of Gamergate has (hilariously) become the go-to analytical lens through which semierudite internet dorks have come to interpret the course of history. They've misunderstood everyone's general revulsion by specific acts of sexism and harassment as a license to invent a whole politics which places them above reproach. Because these are generally middle-to-upper-class liberals, often employed in the white collar media or tech industries, these people are used to living a privileged life sheltered from controversy, and see that as the natural order of things. The flamewars of Gamergate were, for many of them, literally the worst thing they have and will ever experience, even when they were not actually subjected to anything actually qualifying as harassment; this is why they'll even mobilize their arguments in defense of drone strikes or a neoliberal war criminal. The murder of powerless, innocent people overseas is just some abstract intellectual problem for them (if it's a problem at all), but the danger of getting owned on Twitter dot come Has To Stop Now.
A major nuance these people seem to have missed is that the popular critique of Gamergate was not just a critique of sexism and harassment - it was also a critique of the ridiculously disproportionate liberal-nerd fixation on the entire controversy. For instance, hilarious gimmick account Moms Against Gaming relentlessly trolled all gamers with spurious arguments that video games are responsible for international terrorism; and whether you were in on it or not, the joke was obviously that many gamers had lost all sense of perspective.
As a bystander, it's pretty clear to me that this trend continues today. And not just with the Gamergate dead-enders like Milo Yiannopoulos and the usual Reddit teens and anime-avatar trolls. An embarrassingly huge number of liberals and nerds who barely had a thing to say about the civil war in Ukraine, or Fight for 15, or the murder of Eric Garner are still talking about Gamergate like my grandpa talks about The War. I don't really expect them to change, any more than I expect my grandpa to change, but The War was much bigger than anything you've gone through, and I don't think it's relevant to everything, either.