True, T-Ball used a soft baseball, I forget the name but my older son's T-Ball team which I managed went 20-1. A cup was not necessary.
I'm old enough that my first cup was metal, a loud clang was heard the when the pitcher hit the dirt and short hopped the cup.
I wore the tools of ignorance from 9 until 24. The plastic ones didn't ring but still were painful on the edges.
T-ball is for 4 or 5 year olds, but you didn't even really need a cup in Little League even as a catcher, because they had those front protector things that go down and over the groin area. They don't in professional baseball because it looks unprofessional.
O.k., I have seen pitchers get racked in LL, but it's not super common.
I didn't play professional baseball (though I did play against some in winter leagues in San Francisco, some retired and some in the minor leagues) but I caught and wore a cup in Jr. Hi, High School and in amateur wood bat leagues in SF on week ends until I was 24.
Pitchers in the latter leagues could throw hard, but did not necessarily know where the ball would go. Most tossed fastballs with the occasional curve or change up - some would catch too much of the plate when given a pitch out sign.