It's strange that, to some, this is somehow a controversial statement.For a conference to say "we couldn't find enough subject-matter-qualified women", one of the following must be true:
* The least qualified speaker on their roster is still more qualified than literally every woman currently living, or
* Something about their conference failed to attract (or worse, repelled) half the population of the planet.
The first is statistically extremely unlikely. The second is more likely, and represents a problem with the conference rather than the pool of potential speakers.
Unfortunately, telling people "the problem is with your conference and not with the pool of speakers" is a controversial statement despite being painfully obvious.
This is without getting into the "faux diversity" insult which implies that there is something about women as a class which naturally makes them less qualified (since, obviously, conferences select purely on qualifications and just coincidentally end up heavily or often entirely male) -- if you didn't believe women are inherently less qualified, you wouldn't think that having women speak was necessarily a relaxing of qualifications or only done for "diversity".
Here's another true-but-sadly-controversial statement: if you believe what you're saying, then the kind of tech conferences you'd likely run are actually affirmative action for people who look and think like you. And I bet you wouldn't want anyone saying you only got in because they give preferential treatment to people like you, right?