Well their Coax system can deliver faster downstream speeds than FTTC can, so not sure how you can say that.
Cable may well be able to deliver higher headline speed but it runs into problems if many of the subscribers actually start to use those speeds for a sustained period because the local bandwidth is very limited - typically several hundred users on a pipe that can do 200Mbps down and 18Mbps up and VM were selling unlimited 100/10 on that infrastructure until very recently.
You happen to know that every single Virgin Media hub/pipe has 'hundreds' us users sharing a 200mbit bandwidth connection? Source for this information?
Im aware of congestion in some areas but many people are happpy with their connection and do see the headline speeds on a regular basis.