Comment by burnt-resistor

I did consulting work for a place with Sun 2's and 4's, AIX, HP-UX, Xenix, and SCO. There was NFS, Netware, and UUCP all cheerfully coexisting on an IPv4 network that used a public Class C for NATed internal use. (It's now a zombie IP range that doesn't do anything useful.)

Later, I wrote code a university that had even more heterogeneous clusters.

The problem today is the siloification and bias against system diversity that doesn't account for proper software configuration management and support of multiple platforms. Portability is a dying art.