The "how" is an easy answer. Nobody actually sets up a whiteboard and announces
"today we are going to learn proper shouting techniques."
(Unless you're a character in Douglas Adams' "Hitchhiker" series- the Vogons had
officer ranks like "Senior Shouting Officer.")
They taught BY EXAMPLE. If you're someplace where you are told EVERYTHING is PLANNED
to the nth degree and it's ALL spiritual, then there's significance to how the carpets
are vacuumed, the lightbulbs are changed, etc. (Yes, they taught how to vacuum the carpets.
Really.)
So, when leadership spends lots of time SHOUTING about things, then you get the lesson that
SHOUTING is part of being a leader.
You have a good question as to "why". I think it was laziness.
By that I mean, vpw and lcm had poor self-control and shouted all the time.
So others absorbed that, and thought it was INTENTIONAL when it was just that leaders
were too LAZY to police their own behavior. It's the same with all the CURSING.
vpw and lcm cursed a lot in private- lcm did it in LESS private venues.
So, people learned to curse. At least one parent said their child LEARNED TO CURSE
through sitting through lcm's (MANDATORY) lunchtime tirades.
Imagine-
there you are with your child, eating lunch.
Then some maniac tromps up to a microphone, and spends 20 minutes yelling and cursing
on a subject.
Then he pauses and changes subjects, yelling and cursing for ANOTHER 20 minutes.
How can you tell your child to control himself when the supposed leader of the group
is more impulsive than your child? The most hypocritical part?
Children on-grounds in twi are frequently BEATEN if they're not behaving PERFECTLY.
Adults were REQUIRED to all carry a wooden spoon with them at the family corps so they
were prepared to beat ANYONE'S child at any time. Yet the leaders were the ones allowed
to be brats and terrors.
(Oh, if your parents were big muck-a-mucks, there was always an excuse and you could
manage to escape punishment for committing CRIMES and trashing things. Otherwise,
children were in terror of adults and sometimes other kids there.)