Eh. The "inefficent calorie conversion" take is sort of lazy and misses the nuances. I just looked it uo, and it seems that only about 55% of yields are for feed, and there is definitely some more nuance there, since a lot of feed meal comes from stalks and parts if the plants humans would not consume. This notion of calorie inefficiency also misses the mark on what would be planted and harvested instead to contain the same bioavailable nutrient profile thay comes from meat. In otber words, using land for feed to convert grains to another type of food is probably more necessary than just "taste".
I don't care to research it further, but I own a small 5 acre farm and can attest that some crops grow in some areas and some don't. So even if you did map it all out on a piece of paper where you'd get all your beans and lentils and whatnots I doubt it would work in real life. Cattle can handle a couple hard freezes. My tomatoes can't.
There is, as you say a lot of nuance here. Making cattle go away doesn't suddenly make say 55% more wheat suddenly appear on market shelves.
Indeed the argument to remove beef production has always struck me as an interesting starting point to a longer conversation.
So ok, cattle are gone, and there's now say 30% more grain on the market. Presumably this lowers prices to humans? Do people suddenly eat 30% more bread?
Health, and weight, issues aside (not sure an increase in carbs at the expense of protein is a win), do people just shift to other protein (like chicken). Does this mean a huge oversupply of grain, and a consequent drop in prices?
Let me put it another way. Does removing a market currently consuming 30-50% of the crop make things better or worse for farmers?
IMO Having livestock feed as a market keeps prices up, and as this article points out they're still too low. Killing off the cattle market kills off grain farmers too. I'm not sure that's the win people think it is.
You’re right that a lot of livestock feed is crop residues/byproducts humans don’t eat—but that doesn’t make beef “necessary” or erase the land/opportunity-cost problem. Globally, ~36% of crop calories go to animal feed and only ~12% of those feed calories come back as animal-product calories (Cassidy et al.). Livestock still consume ~1/3 of global cereal production (Mottet et al.). And in full-system LCAs that include grazing + feed land, meat/dairy provide ~18% of calories and ~37% of protein but use ~83% of farmland; cutting them can reduce farmland >75% while still feeding the world (Poore & Nemecek / Oxford). Plus, even if pasture isn’t croppable, it can be restored—land used for animal foods has a big carbon opportunity cost (Hayek et al.). Nutritionally, major dietetic bodies say well-planned vegetarian/vegan diets can be nutritionally adequate, with attention to nutrients like B12.