"Thanks to Unix, we know exactly what happens when everyone does things their own way on the same system: utter chaos. Even if you were on the same hardware and used the same basic Unix you ended up with a mess. For example, UHC, Consensys, Interactive, and Dell (yes, the Dell you're thinking about), briefly all had their own versions of Unix SVR4 (System V Release 4) on i386 processors. You could no more run a program designed for UHC Unix on Dell's Unix than you could run a Toyota Prius on diesel fuel."