Recently I had too much time on my hands and I got to wondering... ::)

My perception is that "everyone" (admittedly, a sweeping generalization) seems to talk about 11o target crowns.
I understand that crowning the barrel protects the muzzle, but...
Is there a reason why 11o appears to be the de-facto standard?
Does it work better than 10o or 12o or some other angle??

I am not trying to pick a fight, just realized I was ignorant of the "why" and figured I'd ask.
Maybe I can learn something today.
Cheers,
Thomae