If you are in America, that 'empty land' was not 'empty land'. It was Native land. Displacement of Native Americans was genocidal and destroyed communities and cultures.

Also, the article touches Moses, right, but it is about communities as a concept, with a heavy emphasis on online communities, where 'new things to buy' do not come at the expense of 'tearing down the old' - and where, when you tear down the old, behaviour patterns change. Take, for instance, the reddit re-design, which changed the page's culture. Or usage patterns of RSS post Google-Reader-shutdown.

You will be pleased to know that I’m not from America, nor have I ever lived there.

My point stands: there are a million excuses not to build more. And when we make that choice not to build, the costs are invisible but they definitely exist. But hypothetical benefits are not as easy to point to as the costs of building.