A vehicle is all wheel drive if it has the ability to send power to all of its wheels, even if this happens only under limited circumstances that occur infrequently or in a manner that is actually not desirable in terms of continued forward motion or overall vehicle control.
Why is this even something that people debate about?
The people who design, build, sell, and regulate vehicles for a living get to define the terms and set the standards; not random people on the internet. This definition has already been set, and it appears that they didn't bother to ask you for your input.
Specifically, in Standard J1952 the SAE defines all wheel drive as being "a vehicle drive system with the ability to drive all wheels". That's the entirety
of the definition.
There is absolutely no mention of "Diff x 3" or any other specifics of the system.
They do, hoewever, make it clear both textually and diagrammatically that there are in fact many different types of systems that are legitimately considered to be All Wheel Drive, and that 3 differentials are not a required feature.
SAE > you.