There is no way to guarantee you get, say, 10 Mbps downstream unless you cooperate by downloading that much. If more than 10 people download from my 100 Mbps-connection server at once, they will get less than they paid for, even if the telco is totally innocent.

People need to understand their mileage may vary.

I seriously doubt people were getting their nominal bandwidth during events such as 9/11 or Obama's inauguration.