That's quite interesting, as in the last 20 years that I've been dealing with Apple hardware they have typically been excessively strict with hardware spec conformance (not especially "liberal in what they will accept"). They of course had plenty of in-house stuff (adb, AUI etc) back in the pre-jobs-departure and pre-jobs-return eras, but that was often because no standard existed at all.
I wonder if something has changed or if this is an outlier, or perhaps it's just my sampling (which of course is hardly enormous) has simply entirely fallen in a pool of strictly conforming equipment. I can certainly believe the last possibility.