A native binary can be verified by anti malware systems, and once installed and working, poses no security risk.

A 0day in a browser for the WebUSB system would allow any website to mess with arbitrary USB devices connected to your computer.

While the browser sandbox is generally safe, it is also a huge target, and with a security risk like that, it wouldn't surprise me if it's a prime target for black hats.

So instead of using trusted vendors or requiring tools with auditable code, we just allow everyone to be able to access the user’s devices?