Thought experiment: early stage startup A, which consists of 3 males throws a private launch party at which there are female strippers. It's unprofessional, but at this point it doesn't matter because it's just a group of friends who happen to be running a company. Startup B, consisting of three females, same situation with male strippers.
Later A and B merge and, to celebrate, throw an event called Hackers and Strippers, which is open to the general (adult) hacking population and features male and female strippers and a guitar shower room. Hard to imagine any hacking gets done, but a good time is had by all. The actual logistics of such an event, and whether or not it would offend their customer bases, are left as an exercise to the reader.
AB grows to become the 3000 employee AB Corp. When they IPO they throw Hackers and Strippers Worldwide. Same kind of party on a larger scale. Unprofessional? You betcha.
Independent of sexism, at what point does unprofessionalism become a problem?
Part of the argument is that this is sexist. Part is that it's unprofessional. If there were also male strippers the event would no longer be sexist, only unprofessional. Would it still deserve moral outrage? Would it still be counter-productive?
I'm just exploring permutations here. I think half-naked dancing girls would make it hard to get any hacking done. But that doesn't necessarily make it a bad event (aside from sexism). A bad event to hack at, maybe.