Most disk drives of the time were like that. One of the reasons the Apple II disk drive was so affordable is that Woz just used the Apple II's own 6502 to handle the grunt work, with their disk drive being little more than a drive mechanism, a PROM, and some ICs. Since this is The Woz we're talking about, he went ahead and broke with conventional encoding while he was at it and instead implemented a scheme which allowed for a few extra sectors per track.
It might be an interesting exercise to see how many peripherals are connected to your PC right now that have much more computing power than an 1Mhz 6502.