I agree that this is a pointless system that can have no concieveable effect on terrorism as it simply cannot achieve its purpose and is therefore an ill-concieved pointless waste of time and manpower.
Isn't it about being seen to be doing something and in turn disrupting any undesirable activity? Prevention better than cure and all that. Don't give these people the intelligence they don't have. If any part of their well rehearsed plan doesn't go right on the day, they cannot adapt to the change.