Apple designed their product to isolate damage to just the USB circuitry, whereas the bad cable seemingly tookout the entire Chromebooo laptop.
The cable attached to the Chromebook was totally miswired and flipped Vbus and ground, supplying -5V where 5V was expected. As the article said, nothing is really designed to handle this kind of failure because it should be blatantly obvious to the cable manufacturer if there were any sort of quality control.
Reverse polarity protection is very common, and often only requires a single diode in series with the +V line, so that current can only flow in one direction.
Seriously though, why would you assume this? The article doesn't state it - it gives examples of both devices being damaged in different ways, but cites only Dell as actually designing their hardware to tolerate bad cabling.
Perhaps Apple has built in some mechanism to protect the rest of the circuitry from a USB failure, but without further information it's more reasonable to assume that the MacBook owner just got (comparatively) lucky here.
Years ago, I shorted out a USB port on a desktop PC, with the same results - system booted and worked just fine, except the USB port was dead. Upon opening the box, I found a popped cap and some scorching on the motherboard; I'd be... reluctant to call this a well-designed failure mode.