Everything is a finite shared resource.
That's the point of ownership.
>The idea of treating land as a pure asset has had a lot of negative social effects and ultimately will lead to a kind of neo-feudalism where the megarich own everything and the underclasses are perpetual renters.
The idea that land is not a pure asset leads to regular feudalism.
I think the point is that (up to a limit that we're a long way from reaching) we can make more toasters to satisfy any additional demand that arises for toasters. But we can't make more land to satisfy any additional demand that arises for land. So we have to share the land in a way that we don't have to share toasters.
Yup. And despite the claims made that it's a solution for the common folk, the people who "own" and can make decisions about the land will be the megarich, so it will be feudalism, with rent due on the land you own.