
When
Knoppix was first released it was heralded as revolutionary in the Linux world. Its autodetection and configuration capabilities were unsurpassed. Many of my colleagues remarked that if 'KNOPPIX can't do it, Linux can't do it'. Theoretically, one would be able to get a Knoppix CD, pop it into an arbitrary system, run it, save one's data to a partition, USB stick, etc....), reboot and the existing system would be left completely as it was before the CD was placed in the system.
I hate to sound snotty, but on low end systems you're pretty stupid to expect KDE to be really fast and use no RAM.
KDE can claim those minimum requirements because they have things like fluxbox and XFCE and other lightweight WMs. They are very responsive on systems of that speed (especially fluxbox). Additionally, Knoppix doesn't require X to be used, lowering the system requirements even more. I'd say their system requirements are probably higher than need be.
Think of it like a game. When a game says minimum system requirements, that means on lowest settings not on maximum at 1600x1200 with 4x Antialiasing and 16x Anisotropic filtering with detail on maximum. The latter is what you're trying to do.
That said I did appreciate that this person did things like timing tests. Those are a meaningful thing in a review. Much better than things like "it's too slow."