It might amuse you to know that the US Marine Corps puts a great deal of emphasis in boot camp on recruits not touching their faces.

I guess it has to do with teaching the discipline necessary to stand in formation for long periods of time without breaking the position of attention.

But in the Marine Corps in general, not touching your face has evolved into an important part of maintaining a professional bearing.

And yes, I agree with you that it is very very difficult. I had a terrible time with it all those decades ago when I was a new recruit. The urge to touch her scratch the face can be just overwhelming at times.