USB Mass Storage won by making flash look like a SCSI disk

Removable storage did not need another file system war. Cameras, flash sticks and card readers needed to appear quickly on PCs that already understood block devices.

USB Mass Storage's Bulk-Only Transport kept the protocol small: command, data, status. Under that, it reused the SCSI transparent command set, including ordinary sector reads and writes.

The result was plug-and-play storage. A gadget could arrive over USB but behave like a hard drive to the host, while FAT, HFS, ext or any other file system stayed above the class standard.

Put SCSI blocks inside USB

Bulk endpoints matched storage's large sequential transfers.

SCSI reuse avoided inventing a new disk command language.

Keeping file systems out of the class spec let every operating system format the same device its own way.

A new connector wins faster when it preserves an old abstraction. Hide the transport change under the interface software already trusts.

USB flash drives, card readers and many embedded devices adopted the mass-storage mental model. Even when faster transports later appeared, the win had already happened: removable solid-state media felt like a tiny disk, not a strange peripheral.