What I take from it is 1) NVIDIA probably has the more true-to-the-original upscaling tech, or they wouldn't have released a pixel-peeping tool and 2) if you need a tool like this to see the difference, maybe the differences aren't that important to most. The bigger picture thing here is that going from 1440 to 4K or such, the improvement for most people is sharp lines or a sense of texture, not getting more information from the image, and relatively simple filters can maintain that.
Improvements on this kind of tech are still useful, but the win is more from getting by with fewer pixels, or fixing the remaining glitches that actually stand out, or better fitting the tradeoffs to what users want (e.g. keep the best quality you can but keep X framerate). Removing stuff you can only see with freeze-frame and zoom doesn't make that much difference to folks.