A lot of “farmland” is unproductive and kept in usage only by heavy subsidies. Additionally, I think a more important/interesting part of the article is taxation of livestock - you reduce the land needed significantly when the amount of livestock is reduced. I’m not vegan/vegetarian but it is “obvious” we should reduce meat consumption for a wide range of reasons and focus on raising livestock in ways that are beneficial to the wider environment.

Yes, the least productive 10% of land represents a much smaller percentage of food production. This is often land in areas that are most environmentally sensitive.

In the UK we pay farmers to raise lamb on marginal land yet they still aren't competitive with lamb shipped from the other side of the world. I'm not sure why we should be subsidising that, especially when there is a lot of environmental damaged associated with it.