Great idea though I doubt it would be easy to gather so many people and keep them interested. People found the maps they like and they don't want to play/learn any other map. The thing you want here is feedback, most of it can be found in Map Development section where people feel like they can be a part of the map's progress, unlike a map that is already out.
Your example of Archer Wars is good, expect the playerbase for that map is really small, and people who would work on it even smaller, on top of that the Wc3 community is small enough to begin with (and divided by language to further the separation). Even the best map maker has something that he doesn't know so I support the idea.