It's true that grass-fed animals don't have the same environmental impact as grain-fed ones. But the problem is that there's no way to produce enough beef to me

It's true that grass-fed animals don't have the same environmental impact as grain-fed ones. But the problem is that there's no way to produce enough beef to meet worldwide demand other than concentrated feedlots. And certainly no way to produce it at the low cost that the market demands. Unless the cost of beef can be adjusted to include all the negative externalities that its production entails (topsoil loss, water and air pollution from fertilizers, pesticides, manure, and diesel fuel, antibiotic resistant super-bugs, public health threats from unsanitary slaughterhouse practices, etc) then meat producers and consumers will benefit from cheaper prices while the environment suffers.