To me, the problem is not scientific studies, but mainstream reporting of scientific studies that turn into popular fads and trends. Science doesn't deal in absolutes, but society does. This is true for dietary fat, autism, gluten, paleo, salt, etc.
Surely I oversimplify, but I think it's important to acknowledge the human factor in what passes as scientific consensus in a field at any given time.
It's a classic case where it's hard to pickup most people saying 'I have no idea', when there is a lot of talk about theory x.
PS: The counter argument was simply children get feedback while learning a language. Mute children have a much harder time picking up their native language so it's not a passive process.