[LeifCarrotson]

It does. Mozilla doesn't trust users to not be manipulated by malicious websites into doing so against their own interests. At GP link 2, Mozilla writes their rationale for concluding that WebUSB is bad:

> Because many USB devices are not designed to handle potentially-malicious interactions over the USB protocols and because those devices can have significant effects on the computer they're connected to, we believe that the security risks of exposing USB devices to the Web are too broad to risk exposing users to them or to explain properly to end users to obtain meaningful informed consent. It also poses risks that sites could use USB device identity or data stored on USB devices as tracking identifiers.

Personally, I'd be happy enough with an implementation of WebUSB that only worked with websites accessed over localhost or on the local network. I want to write data over USB to ESP32s and Teensys 3D printers and so on through an integrated local webserver.

[hot_gril]

localhost-only access is a reasonable compromise