Agreed. But the mechanism also relies on millis(). Or micros() for that matter.
How is it superior to just reading one of the above functions directly?
And if we are agreed that millis() / micros() are drifting, wouldn't the above approach also drift?
From my understanding of the stability of crystals and resonators, they drift based on temperature. If the temp is fairly constant, their deviation from rated frequency should be more-or-less the same, and not all over the place.
I also don't understand why accumulating a count yourself (instead of relying on the millis() routine to do that) is any better than using millis() directly.
If millis() is losing ticks, then any routine that relies on millis() would also lose ticks.