I don't really think the issue with with grazing cattle on land that's suitable for it. I think the issue is that we're raising cattle in places that _arent_ suitable for it.
Take for instance the factory farms which have to constantly ship food in to feed the cattle. Another example is deforestation to create fields for cattle to graze.
I think the OP is right, we need to convince more people that beef is not a sustainable food with the rate at which we consume it today.