Can someone explain why the deal caps carbon output to a set amount per country and not per capita? It seems like it heavily benefits countries like China who h

Can someone explain why the deal caps carbon output to a set amount per country and not per capita? It seems like it heavily benefits countries like China who have many more times the population of smaller countries who are currently trying to increase their population size. It seems difficult to reduce carbon, while adding carbon based lifeforms that breathe carbon, eat things that create more carbon and use electricity which creates more carbon.