It would allow them to do HDMI FRL also, which is probably what you mean when you say HDMI 2.1. AMD cards also do HDMI FRL I thought. FRL is what allows things like 4k120Hz (higher bandwidth modes). The VRR that the Dock does is the VRR standardized with 2.1, which is why it works on TVs and devices that do not support freesync (see: LG TVs).
Anyway, the Dock doesn’t have a fast enough HDMI converter to do that. It’s not a licensing issue. Next gen Deck/Dock will probably do it.
I mostly agree, but it would be nice if it was a bit faster to be able to use it for web browsing. I still like reading long form articles and such but navigating and scrolling isn’t very viable yet on e-readers.