Military cadence

[Seamus Fermanagh]

I've never understood why army units have things like initiation beatings/scares. I kinda understand doing it to a troublesome member because he constantly mucks around and acts like an idiot, but doing guy in just for joining?

It is common to most "high trust requirement" teams in various areas: soldiering, fire-fighting, etc. Integrating the new member [FNG] involves the membership determining that they can handle stress and remain "with it" while being stressed. Since they have to trust you, literally, with their lives this takes on a good deal of importance. Add in that most such units have a somewhat higher morale -- with it's concomitant 'show me you are as keen to be a part of this as I was when I joined' -- and the new member "welcoming" efforts make a bit more sense.