[monocasa]

Because even above the physical layer, the two protocols are very, very different to the point that you're nearly doubling the amount of work that you have to do. USB at it's core is a host polled interface that looks like a network, and Thunderbolt is at it's core a multimaster RDMA interface. You'd basically be designing two different devices.

[bryanlarsen]

Sure, but USB is a very cheap protocol client-side. I fail to believe that requiring it in all TB3 clients would be prohibitive.