They did revolutionize the GPMG concept, the problem was in their implementation. In US doctrine, it was (and still is) that the MG is there to support the riflemen. In fact, if you want to get down to it, everything in our military is basically an asset to support the rifleman...
German doctrine was screwed up. The riflemen were there to support the MG. A squad was basically a gunner and a bunch of AGs.
When you got a quickly deployable LMG capable of suppressing anything not behind 1/2" steel, it's easy to see how you could derive that ideology. In terms of infantry combat, the rifleman is sub-par to the machine gun emplacement as WWI proved. Problem was that the days of WWI had ended. The ability to call in light mortars and other indirect, or armored support, pretty much made the machine gun emplacement a liquid asset on the field.
Had the Germans fielded the StG43 in 1943 it would have presented a very interesting shift in their abilities, and more than likely a change in doctrine. I think this is the basis for the AK47 being prominent in the article.
Problem is that Soviet doctrine sucked, too. Bunch of half-trained guys running at you with AKs blazing on full-auto is intimidating and all, but if you've got fire discipline on your side, they're going to be meat on the table... Their infantry doctrine isn't much more than a throwback to the WWII doctrine developed around the subgun, which was a quantum leap for the Soviets. Their rifle doctrine was stuck in the 1700s...