Well paranoia for one, people get paranoid and feel more secure knowing that they don't have an open account that could potentially be used against them if something were to happen to them.
People are also known to be STUPID! If someone becomes "paranoid" then this site it NOT the problem... their lifestyle is!
Don't get me wrong...I understand the user wanting to vaporize their tracks here.....but in all honesty ..... they don't have DB access so even if there was a "false sense of security" delete button..... it's likely their account would be flagged as N.......NOTHING would be deleted..... and life goes on!
If you are paranoid then you probably shouldn't be on the Internet in the first place