[h2odragon]

paper printers only needed such accuracy in one axis of motion, and had gearing to provide it.

hard drives use voice coils, a completely different technology. The circuitry that does that evolved and certainly influenced the creation of microstepper controllers: the neat trick they do is treat the stepper motor as a voice coil in between full steps.

[flimsypremise]

I have several 2-axis microscope stages from the 80s/90s that are driven by brushed motors with position feedback, and they are all capable of higher accuracy than any stepper motor I have. The capability was there, it was just pricey.

Hell, CNC machines existed back then too.

[kragen]

At the time, hard drives used stepper motors, but didn't use microstepping. Paper printers like the MX-80 used stepper motors too, it's true, but didn't use microstepping either. Gearing makes your step size smaller but adds backlash, so it can be the enemy of precision; position feedback like current inkjet printers use is much more precise.