Because the whole "gamergate" thing was not about attacking female gamers. If I recall correctly they were after people who were villainizing video games.
You don't recall correctly. The whole thing started with false accusations of unethical conduct against a particular female game developer (Zoe Quinn), followed by harrassment campaigns and personal threats against that same person.
Their 2 pillars are: opposing corruption in game journalism, and opposing political attempts to discourage violence and sexuality in games. There are many women who support GG. The angle about it being anti-women was consciously created by a woman who was caught in a scandal, and published a fairly high-profile PR article in order to protect her reputation.
Eron Gjoni publicly accused his girlfriend Zoe Quinn of cheating on him with several men, whom he named. One of the men was a games journalist who had once written a few sentences about a free game Quinn made, in a larger article. (Several months before he allegedly slept with her, by Gjoni's own admission.)
This, alone, was taken as proof positive that gaming journalism (and the gaming industry in general) was in the pocket of corrupt feminist interests, and founded an entire movement based on rooting out and exposing examples of same.
The story somehow became that Quinn was openly sleeping with half the games journalism industry in exchange for good reviews of her games. Now that the facts are out, the smarter Gamergaters try to downplay the Quinn episode or pretend that it never happened, inventing an alternate, less embarrassing origin story about ethics in games journalism. Unfortunately, a lot of people seem to be buying it.
Any "ethics" stuff in the original allegations against Zoe Quinn was false in the first place, as anyone involved could have verified with about five minutes of research.