Because the hardware is beautiful and the build quality is (was?) excellent. Recent fumbles like the butterfly keyboard design have definitely reduced that perception, though.
I have a Dell XPS 13 now, and while I like it, it's just not as pretty as a MBP. I recognize that that's a highly subjective judgment, but that's a thing that matters to me. The XPS's build quality is good, but not amazing; for example, I've had it for less than a year, and one of the rubber strips on the bottom of the laptop has been peeling off for the last few months.
Overall it just makes me sad that "hostile platform" is even a thing. At this point I've decided that the alternatives are good enough for me, and the better hardware support tips the scales in favor of them.
It is hostile platform, it should be rough. I use 14" Dell Latitude - no problems at all, beautiful machine. Probably would stay on it or try Asus ZenBook.