See: entitlements people feel about going back to "homelands" in the Middle East, or to Europe after the war. These are not people that owned land, and yet we still feel morally responsible to help them return to their original homelands.
Ultimately, land ownership (or its euphemisms like "homes" or "property rights") can only be backed by monopoly on violence, otherwise known as Governments, in that area.
Do you have a better alternative to allocate land (or any other asset)? Please share so that we can discuss.
But my point was not necessarily that no one should own land. Another interpretation of my question — "Why don't these people own the land they live on?" — would be, why isn't there land around that they can afford to buy and give themselves security? And that has various types of answers, some related the kinds of opportunity in the economy that would give them more income, some about how we can change the supply of housing.
Here are some more developed thoughts on the subject from someone more expert than I am: [2]
[1] https://www.dissentmagazine.org/online_articles/case-for-pub...
[2] https://danielkayhertz.com/2017/05/11/what-is-a-left-approac...
The article about Vienna shows that the forces of supply and demand work very well, given an adequate supply. That seems very instructive.