Those certain services being the ones we actually want to use.
If we only wanted email and web browsing we wouldn't be paying for an unshaped account. A cheep uncapped would be better.
a lot of people get internet for "certain services". If those services are not catered for properly on your network, then for those people, their accounts (overall) doesn't work.
I need to stress that we know that things aren't 100% - and they will improve.