I also got this wrong. After all, disk drives are hopeless contraptions, whirligigs of complexity. Just the fact that your hard drive doesn't croak every hour is a miracle. It performs a feat equal to a supersonic jet's circling the globe six inches off the ground. The evolutionary pace of communications is of a wider spread.
Copper has limits.
The speed was 4 bits per second. Better for your blood pressure to hit the minibar, flick on Spectravision and lie down. Only under perfect circumstances will you get 56K. Optical fiber, though, is stunning stuff. Put a thousand of these threads in one pipe, and, as Everett Dirksen might have said, soon you're talking real bandwidth. Exponential gain paths are not intuitive.