Not every location in the country is suitable for populating. Besides, no sane individual wishes to build over the wild areas and have nothing for either other species (which are vital) nor have any of the beauty of those places to appreciate. So it is of total irrelevance that each individual has a theoretical x amount of space.
We already have cities where we need them, and still we struggle to find accommodation for all, jobs for all, and supply the services needed for the individuals already here.
We inflict urban sprawl into the countryside everywhere in a vain effort to fix the immediate problem but since the population keeps growing more and more it's a fire-fight that never improves.
We can not reasonably grow our population any more, we are not unthinking bacteria on the Petri disk thoughtlessly multiplying as we can until disaster hits. But that said it seems many seem to think that is exactly what must be done. Maybe there is no hope for the human race.