Every USB device that the browser has access to will have a driver that the OS uses to expose its functionality. It doesn't matter whether that driver is built into the OS or not, the OS driver would still exist. The only other option is if the browser is managing hardware outside of the control of the OS by running with lower level privileges, but that opens up an even bigger security risk.

You suggested in another comment that you had some prior background in this area, are you involved in the development of this new web API?