Some of us have no problem with it.
I’ve run into plenty of guys who simply lack the experience/education in that side of life or are truly intimidated by it.
I’ve seen guys who can talk a good game, get leathered up and ready, only to see them shaking with nerves at the point of entry or starting. Had one guy who could stop shaking with nervousness once, and ended up throwing up a few minutes later. Needless to say, the session didn’t work with him.
But some of us are comfortable with it.