The only issue you’re missing is this. If 5 dairy plus 5 meat cows yield 20% more total food now than 10 cows yielded then, focusing on the perceived waste of not eating a milk cow is fallacy. Is there a substantive argument that we are using cows less efficiently than we did a century ago?
What most people drink might as well be colored water given all the fat gets filtered out of the milk
Per the Mayo Clinic, it’s tough to beat dairy milk for balanced nutrition. That is even (or especially) with the excess fat removed and reserved for other products. Switching to an alternative is generally a nutrition problem. Only fortified and unsweetened soymilk comes close.
And one could argue it is the least palatable alternative. Calls to mind “instead of a doughnut, eat an apple”-style dietary replacement advice. Except in this case, there’s no huge nutritional gain like those stupid “instead ofs” have.