The 16-bit device ID is then assigned by the vendor.

The first six bytes is a unique device ID.

For example, USB devices broadcast their manufacturer's ID and their device ID to the host operating system.

What worries me is that according to the article the device ID is available to code running in the browser.

The device ID identifies a specific device from that manufacturer/vendor.

Another theory might be that Apple keeps the device ID cached until a new AppleID is registered from that device.

A device ID and type, combined with IP address and sites visited could be combined to finger users for all manner of embarrassing things.

We have exactly the same thing, a 48-bit unique device ID for every single Bluetooth device.

The device ID is sent back across the bus to the BIOS.

It was the device ID.