Like all metaphors, the pets vs. cattle one started to break down if you poked at it too hard. But it came from a place where individual servers were highly valued and were often at least somewhat unique. Standard operating environments had been around for a while but the "monitor the server's health and nurse it back to health if something's wrong" sentiment was still pretty widespread.

Even redundancy tended to be hardware-based to a significant degree. How much did the IT industry put into things like failover Unix clusters (and VAX/VMS etc. before that) over the years?