The point is that because USB is a master/slave protocol the functions of two USB-C ports on a USB-C dock has to be split up to allow for more than one master. The laptop is the master of the data portion and the power brick is master of the power portion. It's rare to see more than two USB-C ports on a dock because the USB protocol doesn't really allow for more. If a dock has more than two USB-C ports then the other USB-C ports will have some limits on the port functions to avoid having to deal with more than one master, or the dock is using a more complex protocol like Thunderbolt that is not master/slave but peer/peer.