Mostly it's the authors ignorance of the standard. Just because you can connect a display to an USB-C port doesn't mean that is taking up USB bandwidth or requires the CPU to do more work than previously. It's just more ports integrated into one.
He's clearly talking about 1, which is by far the most common scenario, certainly on Macs, and in that case it does require bandwidth and CPU cycles to run at full speed. If you also want that usb-c port to support thunderbolt and all its features you need even more pcie lanes and even access to the gpu.