This is the first I've heard of a lot of beef produced on semi-arid land incapable of supporting anything else, any source on that?

There are large areas of British Columbia not at all suitable for farming due to lack of water, or mountains, but you still see cattle ranchers. On top of that, most of Alberta is classified as semi-arid because the Rockies block the vast majority of the rain. Alberta is easily the largest supplier of beef in the country. Crown land in both provinces gets opened up from spring until fall to allow for cattle grazing. It's fairly widespread in some parts of the world.

This is a pretty basic fact about agriculture but you'll find people are selective about sharing facts when they have a narrative in mind. There are VASTLY different environmental impacts which depend on HOW you raise an animal, not just if. (and places where arguments about water usage per animal are pointless because water is very plentiful)

It is also a pretty fundamental driver of much of human history and caused a lot of conflicts when you'd have migrant/nomad peoples who either followed wild herds or managed their own herds and peoples who stayed put, owned land, and planted crops -- both of these strategies often driven heavily by geography not by choice. These people would meet at the margins and there'd be war.

There are a million sources but here: https://clear.ucdavis.edu/explainers/cattle-and-land-use-dif...

There are plenty of places around the world where you have maybe a hundred acres per animal or more. Whereas the best farmland can support one animal on the order of an acre of land.