by huffa2
I can't remember if "Draw" is spelled out in the rules or not.Rightly or wrongly, the rules might assume that the players are experienced gamers who have played a couple of deckbuilding games. Such players know that "draw" means "from each players' draw decks to be added to their hand and not discarded until the end of their turn."
You mention the game will take forever if you don't draw from the main deck but having these cards run out is only one game end condition. The other is to exhaust the Super-Villain pile. I have never seen a game end by running out of cards in the main deck.
Also, if you could constantly draw free cards from the main deck this would negate the importance of building up your power to earn those cards to put into your deck.