The reason I'm surprised has nothing to do with any advocacy. It's just that whenever I look around at a non-Apple dev conference in the US (Web, for example), it looks as though fewer than 1/5 of the machines are NON-Macs, while the answer to the question above is the inverse: fewer than 1/5 of devs use Macs. (Though multiple answers were allowed this still says that fewer than 1/5 use Macs.)
So, I'm wondering: Are StackOverflow and US dev conf attendees significantly different groups? (Ex: SO hobbyists very different from conference pros?) Or do devs usually install Desktop Linux on Mac hardware, and I don't realize that half of the Macs laptops I see are running Linux? Or do people use PC desktop hardware for development but use Mac laptops for portable use (ex: attending a conference, but they would still qualify as Mac users)? Or are all of the non-US conferences solid walls of PC hardware with so few Macs that they overwhelm the Mac usage in the US? Or have things changed significantly in the past few years? (I haven't been to a dev conference for a while.)
Or what? Presumably all of the above to some extent, but am I missing something big?