[aredington]

Sexism isn't a problem that exists in conferences, it is a problem that is pervasive in the industry surrounding software. In that industry, women are a minority of workers, and they enjoy fewer privileges than their male peers.

When a person presents at a conference with material intended to be humorous, but where the humor excludes women, it is adding to the problem that women do not enjoy an equal position with men. It reinforces that this is an industry where men are privileged, and sets an example for others of privileging men.

I can't imagine someone publicly defending racist jokes included in a conference in this day and age. Even if it's "just a joke", it excludes members of the audience based on circumstances of their birth. The same applies equally well to sexist jokes which exclude members of the audience based on circumstances of their birth, yet people are willing to publicly defend the choice to be sexist.