[dotnet00]

Customer pays for say, 1Gbps bidirectional. ISP has a total capacity of 1Tbps. They find that the average usage rate from users is 100Mbps bidirectional, so they sign on 10x as many users as they could truly offer a full 1Gbps to, taking a risk. Then new services come along, and the customer average usage increases to 500Mbps.

Instead of upgrading their total capacity, reducing their user count by 5x or reducing the speeds they promise, the ISP decides that it's the service's fault that they can't provide the 1 Gbps they're selling. This is obviously double dipping. They want to both sell higher bandwidths than they can provide, and charge others for making them have to provide what they're advertising.