The fandom of my youth is the almost eerily egalitarian ranks of the Bujold fandom. The nature of that fandom makes it well-nigh impossible to be gender-blind, even with the best intentions. The source series has strong male and female characters, working in and out of local gender roles, not to mention strong hermaphrodite, strong neuter, and strong transgendered characters. It makes the fans far more aware of gender issues in the local universe, and a fan sympathizing with Elena's wish to be a soldier on male-dominated Barrayar can hardly be consistent if trying to say "You, wrong gender, out of my fandom."
But LJ fandom is heavily populated by the strongly female-centered slash fandoms. We don't really have a 'boys keep out' sign put up, but once the slashers have set up camp, it's no longer easy to be male in that environment. I don't imagine that it would be necessarily a comfortable experience for a woman to enter an environment populated with men who have made it publicly known that a) they watch porn, b) they, er, *enjoy* porn, c) they prefer woman-on-woman porn, and d) they're proud of all of the above. Some women would be perfectly comfortable with that, but it would give no few women pause about entering that space. (The comparison isn't entirely equivalent, because I don't think a man would necessarily have to consider the thought that he would be physically assaulted and harmed upon entering a female space, and a woman entering a male space does often have to consider if it will be physically safe, but I don't imagine it's an entirely comfortable situation for either.) The rules are a little different for gay men visiting -- I don't know what they are, but from my perspective as a reader and very occasional writer, it's like they're honored guests and consultants -- like the celebrity guests of honor who helped make there be a show to start with so there could be a fandom, but now the fandom has taken the ball and run with it, and they're standing there bewildered by all the fuss and not hip to it. (Gay male slash readers, what say you?)
Somehow, when we weren't looking, we put up doors of lovely male/male porn around some fandom space and started raising young'ns in it. It's not all about the porn, but there are cheerful slashers out there in their very young teens writing some very, very ... juvenile ... works, imitating their elders with cheer. Of course Albus Severus Potter and Scorpius Hyperion Malfoy are meant to be together forever! It was never in doubt! JKR closed the door on Harry Potter's love life, or so she dearly imagined, so a group of disgruntled and bitingly sarcastic worldly slashers declared AS/S as the 'ship of choice from Deathly Hallows, purely tongue-in-cheek. After the immediate rush from the upset contingent came the junior slashers, and they transformed the 'ship.
There used to be all these awkward fics where Harry and Draco wound up in different Houses than canon had them, and re-imagining of the events of the series and especially the dynamics of the characters as it would have been had they been Sorted differently. Now they take the blank slates of Albus Severus and Scorpius and try it out with them. I've noticed a trend in those. It's just a little thing, but it awes me and gladdens me and confuses the living fuck out of me. Homophobia is the big evil. Our little darlings, they have been raised so safe and close that of all the evils in this big world they could choose for their heroes to throw themselves against and be tripped up by, and they pick homophobia.
The resigned acceptance that Some People Are Just Going To Be That Way and the quiet evasions that mean moving on and moving away aren't the end of the story as they were in ... dare I say it? ... my generation. That's where the story starts. "Am I gay?" is a valid point of the teenage identity-forming process now. It's happy hijinks when the two best friends don't realize "Oh, you're gay? But I'm gay!" If someone does not embrace the happy couple, they're either hunted down into a grudging acceptance of the happy couple, or ridden out at least into social exile forever. No other villainy is needed.
I don't know if this is something caused by the fandom space that's been created, or if blatant homophobia will now make you persona non grata at the high school level. There's still all sorts of magnificent asshattery that one can get up to in fandom spaces. The Fandom of the face-to-face old-school conventions is a different Fandom than the online-connected one that organizes meetups. Fannishness is getting more social, and more socially ept. (The painfully awkward get over a lot of the awkward online, and those of the tin-ass-hats get smacked down online a little more rapidly, where there isn't the delicate balancing act of 'well, they are unbearable, but they are also Fen, so we cannot really do anything...' going on.
The size of the community has allowed us to start self-selecting, self-policing, subdividing, and schisming. It's not the only game in town anymore. There are still people who can guarantee that $OUTCAST can never show their face in this fandom again, but it's only 'not in this fandom' now. You don't have to move to a new town. You might have to stop going to this con or that con, but there are enough communities online that you can find a group that matches you -- heck, you can find a group that's been ejected from the same place you just got tossed from. You don't have to always play nice, because these things can be left behind. You can afford to be exclusive, because those who don't fit will find a place somewhere.
That's where modern fandom differs from the old-school. There was always a place for fen, before. There's still got to be a place for fen now, but it's a subtly different form. There has to be a place now, because there are enough people so that like will band together and one of the kindred will have already created a space. There had to be a place then, because we were Fen, and Fen stuck together, and a place would be carved out and made for the newcomer somewhere in the matrix of the social group. You had to do something pretty drastic to lose that place entirely. You could be shuffled around and treated like a political hot-potato or a social disease, but there was still a place, at the end of the day. It was your place by right as a Fan, not your place just because you happened to fit the mold of Fan that they were looking for.
Online fandom can afford to mark off areas as a specifically female space if they want to. The worldview that stressed community built off that single point of similarity in the face of a host of drastic clashes is gone. Exclusion is not an alien notion to modern fandom. We're no longer so rare to find that you have to treasure the company of that jackass just because he's a fan. And we're no longer so rare that we put fandom first before gender identity.