Oh I've seen lots of "good" paper models. I know they can look "good".. But you can't get any decent curves out of them without making complex curves, which have seams, and are quite visible. Having well-printed card stock helps hide seams, but they're still there if you look closely.
The reason a lot of those paper models look so good is because the printing (or depending on the person that builds it, the paint finish) -- it breaks up the lines of the geometry, making it harder to see. If you know what to look for it's still there, though.
If you put a model printed like some at the link you gave, and then a model identical to it but on white card stock, you'd be amazed how bad they look.
In photos they look great. Up close and in real life you start to see the flaws.
I think the people that build good ones show a lot of skill, don't get me wrong. But as a medium for model building it is inherrently flawed and always will be. Paper is inflexible, unsuited to curves and round shapes -- and most things have curves and round shapes, so whenever you model in paper you're always compromising. That's just my 2 cents, and why I prefer plastic models (less of a compromise)
P.S. I don't know if it's "cheating" or not -- but some of the details -- gear doors, gear struts, wheels, etc, are not paper on some of those planes. I always made mine out of paper, but they usually looked like crap -- which might be why they didn't use paper lol!