It is very much not dead and is used for educational products all the time.

We use it ourselves for our internal ecommerce backend system.

We made our own WebUSB Postage Scales and Label Printer that enables 1-click creation of consignment labels.

We pull weights from the postage scales and chuck raw ZPL over the wire to the Label Printer.

Being able to skip the bugs in operating system printing queues is amazing.

Demo:

https://vimeo.com/334547755/c387957a25

It's also used to flash Android devices too.

I haven’t tried it, but WebUSB has been used for loading custom operating systems while hacking Nintendo Switches: https://webcfw.sdsetup.com/