It's not densification if it's "from scratch", that's just building something dense. So in short it's apparently impossible to make a city denser than it alrea

It's not densification if it's "from scratch", that's just building something dense. So in short it's apparently impossible to make a city denser than it already is. But this is trivially false. Each city's density varies with time. I live in Hamburg, it could certainly be denser.