From that How Stuff Works page:
"Usually, when carmakers say that a car has four-wheel drive, they are referring to a part-time system."
i.e. marketing term. "Usually" and "referring to" means common usage, not definition.
The article is also written in an offroader-centric view, which means its not entirely suited to this thread where people are talking about sports cars.
I'm not convinced that the Hummer's system is the "ultimate", since it has to use electronic brakes to limit slip and shift drive to the other half-shaft when the torsen diffs reach their differential limits. A clutch-pack type LSD would not require you to waste brake pads doing the same thing, and it would be a purely mechanical solution.
When an Australian offroad magazine took 3 cars (two using an ABS-based limited slip setup and one using LSDs) the two electronically LSD'ed cars failed while offroad due to electronics failure in the sand and needed to be towed out.
Also, from a sports car perspective, the Evo Lancer's entirely active differential system is far superior to the semi-mechanical Hummer's.
From a purely semantic point of view, if your car has four wheels and all of them get power at some point is there any technical inaccuracy between calling them 4WD or AWD? All wheels = 4 wheels on practically every car on the market.
"4WD" and "4x4" have the connotation of a high ride height offroader, given that this is traditionally the type of vehicle that supplied engine torque to all four of its wheels. When companies started putting similar drivetrain layouts into regular cars, they needed something the customer could immediately differentiate it.