Disk drive orientation

[musicman691]

As anybody who's been into electronics and computers for a number of years knows one tends to collect a bunch of stuff. Well I was sorting through the piles of gear in the space in my basement that gets shared between my ham radio station and some of my trains and found some old hard disk drives. On some of those drives were stickers saying 'only use this drive in a vertical postion' or 'only use this drive in a horizontal position'. These drives are in the 30+ year old range.

I know modern drives don't care about how they're oriented in the computer but was there ever a legitimate reason for the labeling on these old drives? Would it have had anything to do with the drive bearings and their construction?

I'll not even get into the 8 inch floppy drives I have