I get what you guys mean, but what I mean is that parallax scrolling on the PCE, or any other system that only has 1 BG layer, is inherently more impressive than it would be on the SNES or MD, because those two have extra layers to help them with that...
The mere fact that you have to do trickery to pull it off, even if it's just putting some sprites behind the BG layer and moving them at a different speed from the BG's, still makes it something special to me personally, because you know, by virtue of only having 1 BG layer to work with, the system was obviously not meant to do multi-layered scrolling backgrounds... And yet a lot of games did it, and that's amazing!
I'm aware older games also did it, and they're just as impressive because of that, but the PCE just so happens to be capable of producing pretty damn great graphics and sounds on top of it! No wonder why I gravitated towards it, it's got the best of both worlds!