But beyond that, active threats or hateful expression is probably not the dominant type of behavior that might help explain the situation. Rather, it's more what some other members have mentioned: over and over and over again, in all fields of online activity (and in most professional and employment fields too) women report the same thing: unwanted attention from men; friendly overtures that have clear undertones of a hope for a romantic connection; slavishly flattering or conspicuously enthusiastic interactions, which often come with the risk of things turning very unpleasant if the women tries to gently ask the guy to back off or in some cases if she even just tries to discourage the behavior by not responding to it very often. Anyone wanting to find objective corroboration of these common phenomena will have no trouble doing so with a quick search of the academic literature.
Now, whenever I write something like the above paragraph, inevitably one or more of my fellow dudes jumps in to say they would never do that and none of their friends or the folks they've come to know on the forum would do that, and they know this or that woman who's into the hobby and has never complained to them. Here at ASR we should know better - that's anecdotal information, not data, and it also includes an overestimated level of certainty about what your friends might or might not have inadvertently said or done, and what your female buddy in the hobby might have actually experienced over the years and possibly just never mentioned to you.
Anyone who denies that women are treated differently, and treated that way often enough to be systematic (which is not the same thing as intentional), is either delusional or too defensive to admit the obvious reality.