When I visited some of the smaller pacific islands the question of unemployment benefits came up and the response was basically what you describe. On the island

When I visited some of the smaller pacific islands the question of unemployment benefits came up and the response was basically what you describe. On the island there's enough room for everyone to live and grow food and take care of themselves. Presumably with the help of others if they are incapacitated. I'm not sure how that can work though on a global scale of 7 billion people while also allowing for the aggregation of people into cities that is so necessary for everything our modern civilization builds. On top of this naturally you now have unfairness in the system as some peoples land will be better than others, and by virtue they will be richer than others through greater productivity. In the end UBI works around all this and simply says - let the market sort it out, so that the best uses of capital, land, people's time can be found, but we're going give people enough to live so that if the most efficient result is that half the population sits on their hands and the other half work programming robots, then from a systems perspective we are adequately compensating those half that sit on their hands for their misfortune not to be a robot programmer.