Different systems have different compatibility issues with software and operating system compatibility. All machines run on Macs and PowerMac, but one or two still don't have full native code for PowerMac, which slows them down noticeably. If you need to image slides directly from a workstation, there are lots of issues and incompatibilities. To bring text and other objects from workstations, to Macs and PCs, there are other requirements. Certainly in the world of film recorders it is living up to that promise.
Postscript solves many otherwise impossible or complicated compatibility issues.
Postscript is needed to get acceptable output from many illustration programs, including Freehand, Illustrator, and Canvas. Corel Draw and others will also produce better results with Postscript, but you can get away without it. Therefore, Postscript lets you produce the best graphics illustration output, and it provides you with the software compatibility to image workstation files on Macs and PCs. Unfortunately, these traditional, non-postscript compatible drivers, often can only work with a very limited number of programs. Film recorders are not network savvy.