I believe it's true too. Yes you can have oversupply but your baby (unless it has a medical condition) can't overdrink BM. Which is how your supply eventually regulates (though not always - with my 3rd child, I always had enough to feed a small nation).

But I do actually think you can't overfeed a BFed baby.
This is true.

My GP (Who I don't see anymore) was a shocker. When I was having probs breastfeeding Aurelia, he goes "You can't keep breastfeeding just because you want to. There aren't any real benefits to breastfeeding beyond 3 months anyway." And another GP; "You co-sleep? Well that's a problem in itself"

Moral of the stories: "Medical Professionals" aren't always right!