I think you guys are just realizing how crucial it is to have people know choke points as SI. It's easy to just walk in the front as a survivor not knowing how to play at all and breeze by. For SI, it takes everyone knowing what's up.
This is the problem, new players, not how the game is setup.
Games are determined by the weakest link, this is a fact. If survivors have 2 new players and infected have 0, infected will win, etc.