They don't need to be. Stop raising livestock and you no longer need to feed them, which allows us to use the remaining land to feed humans. But livestock only make up a small percentage of human diets, so we can actually give back a ton of land to nature and still easily feed everyone.
a large portion of the land used to raise livestock are grasslands. what portion of feed they are given is also, largely, crop seconds or industrial byproduct. the source for your owid link is largely poore-nemecek, a paper I would trust to tell me the co2e of co2
I'd like to see a source for "what portion of feed they are given is also, largely, crop seconds or industrial byproduct". The vast majority of information I have seen on this topic is that we produce more crops specifically to feed animals than we do to feed humans. Which, just from an energy perspective, is completely logical to me.
I don't see how this supports your argument that eliminating livestock would not reduce land usage. 76% of soybean production is going to animal feed, do you really think that percentage would not reduce if you switched it over to providing food for humans?
69% is a byproduct of soybean oil production. most people don't want to eat soy cake. some people already do, but not enough to eat the entire crop. giving that to livestock is a conservation of resources.
Sure, I don't doubt that humans can't each the entire soy crop in much the same way they don't eat the entirety of other crops. But there is still 76% of the production going towards animal agriculture. You're not seriously suggesting that livestock only use the leftovers from soybean production from humans and produce no additional demand, are you?