Apple has a long history of very enthusiastic fans that can at times crossover into being obnoxious. Apple is hardly unique in that but it does seem to be somewhat more prevalent for them. Some commenters likely don't want to be quickly dismissed as fawning fans lacking perspective of Apple's place in the world.
Apple’s detractors fit this bill far more than its fans do. The online hate Apple gets is nothing short of ridiculous compared to how responsible a corporate citizen they’ve been for as long as I can remember. Most of the time when I see Apple fans in a conversation, it’s countering badly informed anti-Apple circlejerking. One example that comes to mind is the whole Foxconn thing. Apple got massive amounts of backlash for the working conditions there, when virtually every other manufacturer uses them too and received only a handful of the same criticism. Apple dramatically tightened their standards and expanded their vetting process for third-party suppliers (which were already in place). Everyone else? Next to nothing or actually nothing.
It’s completely backward in the same way as the stereotype of vegans. As someone who spent some time as a vegetarian, I quickly realized that most vegans/vegetarians try not to make a big deal out of their dietary choices. On the off chance someone does ask about it, they quickly explain their motivations and hope to move on. Then the next hour of conversation involves something like the omnivores trying to list off every animal type they’ve ever eaten, alphabetically. Alligator, beef (wait, does beef count? Probably not, okay let’s say bison), cuttlefish (wait do individual fish count or no?), etc.
Apple fans (and vegans) get a bad rap because they’re in the minority and those in the majority are simply used to the status quo.
Maybe it's the circles I travel in, but I have seen way more knee-jerk Apple haters--here, on the internet at large, and IRL--than I've ever seen knee-jerk Apple apologists.
Unbridled praise of any large corporation on HN is an invitation to accusations of fanboyism. Prefacing the comment with some sort of deprecation has become a cultural element of immune response to flamewars on HN.