Eh, you can agree or disagree with fanboyism, but I don't see why you find it so absurd. Some people have become really attached and loyal to a brand or product, just like some people get attached to a sports team, a school, a group, a city, a state, a nation, etc.
Marketers use the buzz word "hearty loyalty"
http://www.bus.umich.edu/NewsRoom/ArticleDisplay.asp?news_id=13794
I mean, you're really just questioning human psychology.