I'm from Australia. My theory is that of the subset of people that are interested in both computer science and math, a significant portion use linux and if you use linux, then emacs is the best LaTeX editor (auctex and reftex are amazing). And "doing everything in emacs" is just what naturally happens when you use emacs long enough.

Makes sense. And so did your explanation for liking Rudin above (or wherever it's positioned now).