I wasn't born a feminist, the culture around me isn't predominantly feminist, and no one slipped me some kind of feminist pill or magical feminist indoctrination. I
got to my current ideological position by questioning things when the evidence of my senses persistently failed to match up with what 'the majority' or 'received wisdom' said. So yes, I have questioned this stuff - it would have made my life much easier were it not true.
Next, 'Sexual harassment' isn't a side, nor is it an agent. The 'sides' are 'the sexists' vs 'the non-sexists', or if you want a more 'fighting words' formulation, 'the misogynists' vs 'the decent human beings' (with, in both cases, 'the neutrals' and 'the not-actually-involved's' as well).
The structural power imbalance is really really easy to observe. Look at the reactions to posts like the OP's, both here on HN and in terms of the comments (if their blog has comments enabled) or email they receive.
(As an aside, for this kind of thing Ashe Dryden's blog posts (for example) are better than the OP's at cataloguing responses and providing links.)
There are replies after incident reports like this kind of thing saying that the woman deserved it, or "can't you guys take a joke", or that it doesn't actually happen, or "it doesn't count as sexism, the real sexism is that sexist acts get called sexism" etc etc etc. The people who respond that way seem to honestly feel like they are in the majority - and, as incident reports seem to indicate, many conference organisers act like they agree with that assessment. If there is a mechanism that protects people who perform sexist actions, and protects the protectors, and so on, and no counterbalancing mechanism, then that there is evidence of a structural imbalance.
As for "it happening more than other socially unacceptable behaviour" - we actually have papers that measure the effects of this kind of thing, and their conclusions were uniformly that sexism and misogyny were serious problems with large negative effects in computer science and programming fields. The problem with racism is probably comparable, but fortunately many of the things that have proven effective at reducing sexism related problems also reduce racism related problems, and the two things do not work at cross purposes, so it isn't an either-or problem. The problem with magical thinking and a lack of education might be comparable, but efforts to fix general rationality deficits are often hampered by having entrenched specific rationality deficits, and basic exercises in testing reality and accepting conclusions if pointed at dissolving the various edifices that protect racism and sexism in the industry would advance both causes, so this also isn't an either-or. If you were a marxist or anarchist I could see you thinking that the wage-labour situation was more pressing than any of the above, but again modern marxist and anarchist thought seems to be going in the direction that microfascisms that are allowed to fester will result in macrofascism, plus the whole ideas of perpetual revolution and solidarity, so dealing with racism and sexism are pretty important in order for the revolution to actually be able to win at all.
Does this answer your points?