The problem is with lawns that aren't used except to serve abstract purposes, such as signaling status, adhering to socially conditioned ideas of beauty, or holdovers from the colonial impulse to terraform.

For example, I've lived in my home for nearly two decades and have not once seen any neighbor use their front lawn other than to mow it. Many are the same way with their backyards. Blocks and blocks of this type of land use, all over my city. This is what the nolawns movement is about.