Why would you need any DDU skill for AMD? I haven't used DDU for at least 5 years. It has given me more grief than happiness lately anyway.
Perhaps the urban legend of all AMD drivers suck?
It is more performance out of your hardware at the expense of minor graphical impact. It provides a very useful extra option to tweak games to desired performance, especially on lower end cards. Resolution alone cannot achieve that without actually losing a lot of on screen information. Upscaling doesn't limit the viewport in a 3D game, lower resolution does.
And if the input res is high enough, its a superior form of AA and enables RT; so there is also a place for it in the high end.
I can still personally not prefer it, and I still don't. But I'm not blind to its pros.
I understand and agree to a point on the pluses that you mention, but the only thing that I like of both is the image sharpening, which is better than all the others previously use techniques.
The rest is simply “cheating”, in my book.
That said, it reminds me when Imagination Tech introduced tiles with their PowerVR chips.
Before that, polygons were drawn completely regardless if they were visible to the player, which would take away from the available performance of the gpu, but with that technique, only the visible polygons were drawn, hence providing a boost.
The downside? Everyone needed to pay them for the patent, but we the consumers, all benefits from it without being locked into one vendor.