Well, fortunately for me and thee, this practice will soon come to an end.
There won't be any large gaming companies.
Game engine design will become so simple and powerful that collections of "contestants" will just build their own game. The games will be a collection of add-ons.
The only thing i can say about contests is that entering them, when you have more time than money often gets you seen. And so, it is a good way to break into the business.