It is incredibly efficient if you start with the assumption that raised meat is the required way to feed people. It's not, obviously, and less so every day.

Yep. It was the supply of cheap meat that drove demand. Before large scale animal husbandry, it was super expensive to butcher healthy animals, and comparatively cheap to keep them around for milk and cheese. Pigs and chickens are an exception because they eat everything and they thrive pretty easily.

I'd argue that meat should be the preferred method of feeding people given the nutrients in it.

Okay but then you’re back to not talking about efficiency, aren’t you?

I don't think so. we can be efficient or inefficient with meat as food or vegetables as food.