Because if we applied it to other services...
If they thought you had ordered pirate DVD's by mail three times, they'd stop you receiving or sending mail.
If they thought you had made recipes from a pirated cookbook three times, they'd take your kitchen away.
If they thought you had used a car to take a dodgy DVD to a friends three times, they'd take away your driving licence.
If they thought you had obtained a dodgy DVD in a pub three times, they'd ban you from pubs.
Used electricity to watch pirated content? Then why not have your electricity taken away.
I used to have a couple of photocopied books. Guess I should just burn my library now.
Oh, and remember, they want to be able to do this without due legal process. On the say so of Mandleson's appointed deputies. From the MPAA and RIAA.
Listen, Doubleday doesn't get to check my bookshelves, Warner don't get to check my hard drive, not without a frigging warrant and probably frigging cause.
This is basic, page one, rule of law. We shouldn't have to explain this to a government minister.