If you look back in history you can also see that Unix started at the time of 8 track tape systems for audio and 9 track IBM data systems (8 tracks/8 bits for data, one for parity). Technically very much the same.
At that time the information about the location of files was stored in parts of the information on tape and forward and backward defined when you read data from the tape (like a file, with startposition and end signature); it explains also you why you had not just one FAT at the start of the drive - youdrive—you had multiple to speed up the lookup. And if you had multiple drives they where linked inside of /dev and via the address of the file you moved between the devices.
I beleivebelieve you could have the view that it started simply earlier and that the decissiondecision behind MS Dos area (CP/M) and later Windows NT is simply related to VM mainframe drive letters instead of a single point of entry because at the time it looked more modern, data amounts of today didntdidn't exist and they didntdidn't think that you would eventually end up having not enough drive letters or that it would be over cluttered.
