The comment I'm replying to is discussing things like not flying or not using electricity. I'd describe forgoing modern comforts as primitive.

While infinite growth is obviously not possible I think we are a long way from the population that we could reasonably support on a still healthy planet if we had the technology to do so. I also think that in a hundred years or maybe a little less we'll start to get big opportunities for growth in space, both in the form of doing manufacturing off world and creating new population centers.