The goal might not be permanent restriction but rather practical discouragement. Companies rarely care what happens in the distant future.
If a restriction which asserts non-ownership is imposed on users even temporarily, it can result in potential profits for as long as it stands. By the time it's found to be unenforceable and/or unfair, the people behind it might have made their money and even moved on.
Last edited by Prestidigitweeze; 10-26-2012 at 03:39 AM.