it's not because a product is not made in a industrial fashion that it's de facto good, sustainable or eco friendly. it's like calling natural stuff better than chemical stuff. it's just a common bias.

you can't get meat without giving a lot of proteins to an animal. at the end if you end up eating this protein instead of giving it to the animal to grow tissue you always will win in efficiency.

some will argue that we can't eat grass. that's right we can't. but with all things considered if we eat proteins from plants we can digest, the balance will always be positive, regarding CO2 emissions, natural ressources being wasted like soil and water, and naturally the cruelty.

some will argue that prairies are stocking CO2. yes they are, but the cattle growing on them will produce more.

some will argue that eating soy will give you boobs. I'm sorry but it won't. too bad if it's boobs you were looking for.

etc etc. the scientific literature is quite explicit on this matter. all that I know is that if we decided to switch to a total plant based alimentation right now, we would need a period of transition were cattle or fishing will still be needed in some specific countries with specific ecosystem.