The part where he starts cutting into the cable threw me for a second before I realized where it was going, I actually yelled "WHAT?!" out loud. Seriously unconventional hacking.

Yes. There were disk duplicators that ran entirely on the drives.

You'd upload the program to a pair of daisy-chained drives, put the source disk in one, and the destination disk in the other and they'd go about their business.

You could then disconnect the computer and do other things with it while making all the disk copies you wanted.

I've always wanted a modern equivalent. I thought FireWire might make it happen, but it didn't. And it's my understanding is that USB doesn't allow this kind of independent device linking.

The closest thing I've seen in modern times was a small box I got from B&H that would burn the contents of a CF card onto a DVD-RW.

With a little extra smarts, the drive could deal with ISAM tables as well as files and do processing inside the drive itself. Things like sorting and indexing tables in dBase II could be done in the drive itself while the computer was doing things like updating screens.

OTOH, on the Apple II, the drive was so deeply integrated into the computer that accelerator boards needed to slow down the clock back to 1MHz when IO operations were running. Even other versions of the 6502 would need to have the exact same timings if they wanted to be used by Apple.