It isn't. There is no sense in which "Thunderbolt is basically external PCIe". Thunderbolt provides a means of encapsulating PCIe over its native protocols, whi

It isn't. There is no sense in which "Thunderbolt is basically external PCIe". Thunderbolt provides a means of encapsulating PCIe over its native protocols, which puts PCIe on the same footing as other encapsulated things like DisplayPort and, for TB4 and later, USB.