I think the fanboyism comes from someone getting burned by a company, moving to another and not getting burned.
I grew up during the BSOD windows 2000 era, so my primary experience with Windows/Microsoft was... that they suck. Big, greedy corporation that puts out overpriced subquality software. I moved to Apple and got everything I need, so Apple has earned my loyalty, and Microsoft is stuck in my mind as being terrible.
Apple, in my opinion, isn't as pristine and wonderful of a company (same goes for their devices) as they once were... I think something's going to take the place of Apple as the "hip" company that "works better and is more honest," and I think it's going to be Android.
I know first impressions aren't fair, but that's life and that's the root of the problem.
If the first time you go to a restaurant, the service is terrible, the staff is rude, the food is cold and your glass is dirty... are you going back? Nope. You're going to tell everyone how much they suck, even if your experience was a once-in-a-lifetime oversight by the restaurant.