[jaekwon]

Is this some documented "official" purpose of a patent?

Either way, I have a hard time believing that this is a bigger problem than managing a patent system per se.

Also, there are probably much better ways to protect secrets systematically for the benefit of both inventors and the public.

More plausible is the potential benefit of being able to broadcast an invention and attract investors without having to give up a first-to-move advantage. Elisha Gray might suggest otherwise.