You also have issues of protection. You have people using their PC inside your local network (That is why I use a non-wireless cable modem and use my own Wi-Fi router) So I can control who does and doesn't have access inside my personal network.
From the article: "Comcast says the hotspot – which appears as “xfinitywifi” to those searching for a Wi-Fi connection – is completely separate from the home network. Someone accessing the Net through the hotspot can’t get to the computers, printers, mobile devices, streaming boxes and more sitting on the host network."
Science is what happens when preconception meets verification.