Horse hockey. I am not sure what configuration you used, but I have never had a problem using Parallels & Win98/Win7 running a range of USB devices - hard disks, printers, scanners, camera, WiFi dongles, and even a fairly esoteric laboratory data acquisition device. No doubt Marx55 did encounter problems, but that's hardly universal.
Could be based on an early experience. The first versions were limited in USB support, but I've found no problems with anything (and I connect some pretty weird USB equipment) since Parallels 4. In fact I've found no rough edges with Parallels since 4 with Windows. (Linux is another story, and I use Virtual Box for that, which has inferior USB support!)