Same reason as gangs requiring a new initiate to kill someone. If you have someone expose themselves doing something taboo and you yourself do it too, then a mutual bond is built.
It's far more simple than that. Many men absolutely love sex with new women. Humans are heavily social, and moral boundaries are strongly influenced by those that surround them. It is much easier to break certain moral boundaries when those around you also break them, and this gives men an opportunity to fulfill their desires.
It can be both. The article says there's the idea of sussing out that the different businessmen are "the same kind of person" with similar 'desires'. That's why the article mentions cases of men trying to signal wanting to have wanton sex, but actually going to lengths to not engage in it.
Same reason as gangs requiring a new initiate to kill someone. If you have someone expose themselves doing something taboo and you yourself do it too, then a mutual bond is built.
The article says as much.