This is basically a bunch of red herrings. Most people are not Tibetan yak farmers or the last of some African tribe. These things are not the common case, and

This is basically a bunch of red herrings. Most people are not Tibetan yak farmers or the last of some African tribe. These things are not the common case, and if these approaches ever became the most common way we got those items, it would be effectively the same as everyone going vegan, because AFAIK that couldn't support even a noticeable fraction of our current egg and dairy intake.