Where I worked (a digital electronics simulation company in the late 1980's), we said that PC's had "user interface MIPs" but not "CPU MIPs".

A VAX 11/780 (size of a refrigerator) had more CPU power, but access was via RS232 link to a VT100 terminal. These could be pretty slow: it wasn't unusual to type a command line and wait up to 10 seconds (or a minute, in really bad times) to get a response. And a graph could easily take a minute to fully display on a VT240 graphics terminal.

A PC on the other hand had "user interface MIPs" and could display a graph instantly. What the PC couldn't do is run our very large, 32-bit required simulation code.

(As far as how easy it was to add a hard drive: at the time, to add a new disk to a sun station, you had to recompile the kernel)