Z80 protected mode?

This is simply wrong. Millions of people were using concurrent systems on 8-bit CPUs in the '80s in embedded systems, and hundreds of thousands more were running business applications on 8-bit home computers that spent a lot of their time idling while waiting for user input. Some of us were even running full-fledged multitasking OSes such as OS-9 on small home computers such as the Radio Shack Color Computer (6809 CPU).

This level of CPU power was not a new situation: a decade or two earlier mainframes with not much more processing power than early '80s 8-bit CPUs (sometimes less) were supporting dozens or even hundreds of interactive users.