That's transparent though, and there always have been low level details which were abstracted away from what reaches the "computer". Spinny disks for example pr

That's transparent though, and there always have been low level details which were abstracted away from what reaches the "computer". Spinny disks for example pretty much always had encoding (MFM, GCR...) that is private between the actual platter and the disk controller. You cannot have a long string of only 0 or 1 bits on a magnetic medium, so the encoding makes sure this does not happen. You have to draw the line somewhere, usually at the interface between "computer" and "disk controller" (or at what view the kernel presents to you), otherwise you may as well go down until you reach the quantum physics of it. In a sibling comment, I elaborated on IBM's "CKD" scheme, which was interesting in that regard because it did not present a sequential array of bits/bytes/words to the computer, so the usual "bunch of bits" point of view broke down in this particular case.