What a pointless post....they get lots of calls from people asking useless questions etc, so why not??
The reason why is if someone is deliberately wanting to be a timewaster with desires to do it just to irk the girl. Having that note on the profile means they know it will get to her so it will actually mean they will want to do it to her.
Its like having a sign on your front door saying "no burglars please" this will actually attract burglars as it will give people the impression that there is stuff wothy of steealing and that its easy to break into.
On the other side with the warning of no timewasters, it makes the girl look bad and offputting as it makes her look like she has a short frustration fuse and is not easy going type girl (everyone is looking for a happy go lucky type girl to book with, not someone who gets annoyed and frustrated easily).
And it also makes people nervous about asking legitimate questions of prebooking incase they worry the girl will flip out thinking they are just another timewaster so as a result they don't book at all.
So in all intents and purposes its the worst thing to include on a profile for every different possible reason.