On other hand they can be grown where there is enough land and enough water... Just because parts of the world has lack of water doesn't mean there is lack everywhere. In many parts there is even enough rain.
Are you going to take your bucket out to the Great Plains and capture some of that water?
I can play that game too. Are you going to solve hunger by conjuring more great plains and have the cows graze there?
Because that's the point I'm making. Grass fed beef cannot scale up beyond current production to solve hunger.