When you have to image a highly irrational reason to explain why groups of people do the things they do, there's a decent chance you just don't understand their perspective. They may be acting reasonably rationally from their own perspective. (As you said yourself: "I honestly don't understand...")
I think it's pretty clear that the previous poster characterized the Apple brand as a cult to specifically express the idea that people have an irrational devotion to it.
When you have to image a highly irrational reason to explain why groups of people do the things they do, there's a decent chance you just don't understand their perspective. They may be acting reasonably rationally from their own perspective. (As you said yourself: "I honestly don't understand...")