Partly because we recapitulated the development from 8 or 16-bit instruction sets three times: 1) mainframe (discrete transistors/tubes and magnetic memory), 2)

Partly because we recapitulated the development from 8 or 16-bit instruction sets three times: 1) mainframe (discrete transistors/tubes and magnetic memory), 2) minicomputer (TTL ICs and solid state memory), and 3) personal computers (microprocessor chips). And then there were dial-up and hard-wired cluster controller networks, various LAN networks, and then internet protocol networks to go along with timesharing, client server, and cloud. Plus ça change....