I don't have the time to garden my entire yard, but even if I did, it would come no where near providing half of my sustenance. It takes several acres of farm to feed one person.
If I did nothing with it, it would naturally be grass, albeit extremely tall grass interspersed with thistles, burrs, and hemlock, which are far more negative than grass.
I don't spray it, remove anything from it, fertilize it, or use any ICE equipment to cut it, so that seems like a bit of a strawman.
And a lawn is extremely utilitarian. If you eliminate them, you eliminate a host of positive externalities: they're very aesthetically pleasing and good for mental health, they provide space to do activities, especially for kids, which promotes a healthy lifestyle, they're good for socializing, they're required for dogs, etc.
At least in America, we have no shortage of space. I don't know what people's problem is with people having a little recreational area.