One reason may be that for big conferences, the audience is international, and may no know what is considered ok, inappropriate, and plainly illegal. It also s

One reason may be that for big conferences, the audience is international, and may no know what is considered ok, inappropriate, and plainly illegal. It also sends a signal: several female open source contributors have written about the fact that their complaints has been completely disregarded by the conference organizers. Stepping up publicly against those behaviors would make it harder to do so later, if only from a PR POV.