Why not people when make a seo contest make them so that people has to be on teams of 3-4 persons, if they make them like that they would obviously have to give away more money but the sites that people will do would be much better and much strong
too many cooks spoil the broth. BUT - if you divided the tasks logically, you get good results - just like any real business. you have a graphic designer, programmer, web designer, seo, and manual laborers to submit to directories
Even if the contests don't allow multiple people, I think, some friends can get together and do the effort and then distribute the prize among them !??