I think it was British pronunciation considering that (at least when I was still in school) we also learned to write British English instead of American English.
Later on in high school they said you could write either, but you had to stick to one or it would count as a mistake.
I’ve seen it all around. People dislike it because (I’m guessing) it’s Google’s and because not everything supports it. Used to be worse of course. Over at 4chan they hate it because you can’t upload WebP there (but you can WebM, which is interesting).