geki~ that idea was discussed previously before, as brought up by
marina (follow the short discussion
starting here). It was ultimately rejected for various reasons.
I argued in favor of it at the time it was mentioned, but in hindsight I'm not so sure. Doing that would cut back on the open nature of helping each other to improve. It'd also prevent people from using their works before the contest started, or even during it. I was initially drawn to the contests because I was taken in by
Kasumi Girl's signature and then followed her link to the contest. If people can't show their stuff then forum participation will become stagnant, as "recruitment" to the contests may drop off only to those who already know about it.
In the end I'd prefer to keep it open so that people can receive feedback. I like to think of this more as a community-wide motivational effort to improve, learn, and try new things in the guise of a contest rather than a pure contest in itself