According to this Globe article the average Comcast broadband internet user downloads about a gigabyte a month. But if all Comcast users downloaded a gig a month, the network would slow dramatically for everyone.

And then there are the power users, responsible for high volume downloads. Even though they're paying Comcast for unlimited use, they risk being shut off because they slow the network for everyone else.

There's a common denominator here: a slow network. Instead of blaming it's users, Comcast should build out their network to support the claims they make for it.