OK, I'll bite. Sides of this issue you might not be considering

My theory, which I'm pretty confident about, is that this is a general issue of conferences with mostly male attendees, nothing to do with the free software community.

Booth babes continue to exist at conferences because conferences are full of men with no interest in the topic but were sent there by their employer.

When I see booth babes at a free software conference (actually, I've only seen them at "Linux" conferences), then I know that that stall is a reputationless company selling something with no differentiating features. Red flag for "ignore this stall". Most other LWN readers would also ignore that stall at a free software conference, by my theory.

Then there's the separate category of attendees who can't tell the difference between the companies and who aren't interested in the details anyway - that separate category, which has almost nothing to do with us, is the target of booth babes.