Postpartum fertility...why does everyone say this?

I keep seeing people post that you are "super fertile" immediately after pregnancy. Aside from not knowing when you might ovulate, how are you any more likely to get pregnant than before? It seems to me like the only reason it's risky is because you don't know when you might ovulate....which many women don't even track this and just use condoms, etc. I guess I just don't understand why people say you are extra fertile after you give birth. I imagine tons of eggs dropping all day every day excitedly looking for sperm whenever I read that comment, lol.