Those guaranteed rate agreements are tens of times more expensive than consumer internet connections. The whole reason why consumer internet connections are so much cheaper is that they're based on the premise that most people will have bursty behavior. (Download a 25MB facebook page at 400 mbps then idle.) For such usages, it's far better to let everyone achieve high burst rates sometimes, and then implement policies to discourage streaming at high rates all the time, then to limit everyone to the maximum guaranteed bandwidth the network can handle.