Yes but that's a controller's job ! Of course he/she can make errors, but would you rather take off on a sightseeing heli trip and just hope there's nothing in the way, or have some kind of reassurance that someone, somewhere, is worrying about it ?
Anyone who has accumulated any hours knows that there are blind spots in an aircraft, and the more hours you fly the more you know that 'see and avoid' is a myth.
The more aircraft you bottle up in a small space the more the probability rises that there will be an accident. So it makes sense that in an intensely crowded area such as this, there needs to be control. Not the dead hand of control, just the sensible application of some rules and procedures to keep traffic apart.