It's a short-sighted way of reducing rent. Landlords (which doesn't just include billionaires) continue to have all of their costs increase through taxes, regulations, and maintenance, while not being able to recoup any of it by increasing the rent.

The end result will be that the smaller landlords can't afford it and will have their properties bought up by very large companies.

The alternative is that the government will buy them up, but they don't have to follow any of the standard rules (and good look suing them), which will result in slums.

It's much better to focus on the supply side. Reduce regulations and make it easier to build housing, which will result in a reduction in cost.