"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