The group B approach is exclusively used by organisms with low offspring investment. As the amount of investment goes down, the quantity of offspring increases.

We aren't like that - it takes a humongous amount of resources to raise a functional human. So we either slip backwards from our humanity and become simpler organisms with less offspring investment required, or we have to expand infinitely to gather enough resources. The latter is impossible, there's always going to be some limit to expansion, so we would be left with the former; backsliding.

You're right in that option B is a viable evolutionary strategy, but it's not a world in which I want to live. I'd rather be a person amongst peers than a king amongst idiots.