This analogy breaks down because it's my browser and my hardware. You're essentially putting both the web site and the viewer in a room together that happens to belong to the people who own the site. Whereas the reality is that each party owns his own end of a connection. My house is connected to their house/store. Neither party's rules apply outside their own domain, no pun intended. I can't remove the banners from their store, without permission and they can't display them in my house without permission.