People like ignoring per-capita analysis because it would force them to rethink the sustainability of their own lifestyle. There is absolutely nothing sustainable about every single person living in ultra low-density, car-dependent sprawl.
If you refuse to build dense communities to house people, they’ll just build sprawl elsewhere, and more forest and farmland will be destroyed for it, more cars will clog up the streets because of it, and more neighborhoods will have to be demolished to build freeways because of it.