Complex problems and nuances
I've been turned down for a job because of being LGBT (yup, I was actually told so! This was a long time ago). I've also been hired where it looked suspisciously like quota-filling (this more recently) - and then was clearly discriminated against on pay, although whether that was because I was female or LGBT, or both, who knows? I certainly don't. I've also failed to get jobs because I wasn't the best for the job, and been given tasks within companies because I was the best person for the job.
So much of it is down to the precise circumstances of the situation and the people involved at the time. With regard to gender balance in professions, if there's an existing imbalance, then even if achieving balance is possible (it might not be) it takes time because of stereotypes to be overcomes to attract people to study and get trained, stereotypes to be overcome on the hiring side, and so on. There generally aren't simple, quick solutions. On the subject of innate vs societal differences, hormones can, but don't invariably, cause large differences in behaviour. From what I've seen, some transmen do seem to up their arseholery level a while after they starting taking testosterone under that hormones influence, but most don't, and instead simply become happier, more stable well-balanced people than they were before. Likewise the effects of estrogen on MTFs personality-wise can vary from very little to profound, and can occasionally (but not usually) be negative. There are clearly other factors involved (eg; variable hormone sensitivty, societal and individual expectations of male behaviour and so on)
As for societal factors, I've heard of multiple instances of little girls being allowed to play with their brothers toys, and their brothers being admonished for playing with their sisters toys, but have yet to hear of an instance of the reverse situation. That sort of thing has such huge social inertia that it won't be overcome quickly, and anyone expecting it be overcome quickly is, IMO, either naieve or a fool. Be it noted that the objective of achieving equality does not mean to try to make everyone the same, especially not (heaven forbid!) to try to make males into funny-looking women. The objective is for everyone to be treated fairly and with respect, and it was long ago recognised by feminist theorists that men do get a raw deal in certain ways in life; but women overwhelmingly were treated less fairly and allowed less power; That was the starting point of feminism - to get a better deal for women in the first instance, sure - but also for men to have their lot improved along the way as well. Misandry is no prettier than misogyny.
Unfortunately SJW's tend to scream about whatever drama-queenery grabs their attention at the time as if there were simple fixes. They need to grow up, IMO. I abhor that sort of behaviour, because it's SJW's who have tarnished feminism in many peoples eyes (most SJW's seem to be clueless about actual feminist ideas and theory, but because they scream loudest, some folks assume that what SJW's present is feminism), and SJWs have also caused some disturbingly serious problems within the LGBT community in recent years, to the point where it can be difficult to have serious debate about tricky topics without "covering all the angles" in just about every sentence from the get-go rather than calmly positing your idea, then looking at the various potential consequences one by one in order to try to see how to solve potential problems.
Discussions then get derailed early on over often minor points, and there's some frankly anti-social and downright dangerous crap being put out by SJW's supposedly in support of trans folk, for instance, when in reality they're doing little but making things worse for the very people they claim to be supportive of and others as well. SJW's seem to me to be, for the most part, the trolls of the equality movement, bent on destructive ego-tripping rather than resolving problems.
Personally, I wouldn't lose any sleep over there being no female speakers at a conference unless there was either clear evidence or at least very strong reason to suspect that there was overt discrimination against women going on. I don't care enough about the PHP conference to be bothered to look into the ins and outs of that particular case. There are a few more important things going on in the world that I prefer to spend my attention and effort on, as best I can.