Thunderbolt and USB-C both have theoretical 10 Gbps, both have DisplayPort, both have 100 watts of power. Seems like a fair amount of overlap. Sure the Mac Pro should have several both, but if you are using Thunderbolt to convert to other formats like I am, you can't daisy chain them. Two TB ports is not enough. I have need for at least one more right now on my iMac.