I've always been fascinated by the rarity and elitism of such devices.

However, from a practical standpoint, I don't understand why such low transfer rate device ended up in a bus commonly used for its performance.

Best candidates I can think of were Akai audio samplers that implemented the bus and also had a floppy drive.

For what usage in computers were these devices for?

Note: I am talking about pre Iomega Zip drives era (i.e. 1.44Mb floppies), for which obviously the benefit was evident.