Or do you seriously think an Apple Intel CPU is more reliable than a Dell Intel CPU?
Never heard of Xeon? At least half of a high-end chip's reliability comes from the post-manufacture test procedure and binning standard.
At Apple's scale, they can negotiate any production standard with Intel that they wish to have. This isn't even uncommon, as companies like Google and Facebook are already negotiating custom Xeons for the datacenter, which certainly involves tweaking some internal chip firmware (e.g. changing cache allocation policies or thermal envelopes), all the way up to possibly adding specialized instructions and/or execution units.
Finally, far more problems arise from the mainboard and assembly quality than the underlying chip quality, but at the end of the day it all adds up.
Welcome to Supply Chain 501. It's not your father's Supply Chain 101.
That said, Apple (the company) is a cult-like Black Box of the highest order. When it serves their agenda, they make good products. When their agenda shifts with the winds of fashion—so long, sweet Mini—caveat emptor.
Once upon a time, a very nice product, too bad about the "greatness" removal tool presiding from the glass office.