I have read that thunderbolt and oculink are very different in this regard. Whereas thunderbolt devices can be plugged in at anytime, the oculink needs to be plugged at boot time. This seemingly innocuous detail is the catalyst as to the reason why oculink is better performing. It comes down to PCIe vs Thunderbolt in general.
While PCIe as a standard allows for hot swapping I would be quite surprised to learn that any motherboard or GPU supported it. At least in the consumer space
