Any time you give any kind of preferential tax treatment to some segment of the corporations, capital will move into that segment. That provides funds to the REITs to start buying up the housing stock.
With ultra-low interest rates, the total cost of purchasing a home hasn't gone up that much. What has become the huge barrier is the massive down payment that a lot of people just can't afford. But for these corporations, getting over that hurdle is really no problem. They have just a much easier time gobbling up and privatizing our housing stock and a lot of our other forms of real estate, which they can then use to further leverage to get more loans to further expand the assets. They think of these houses as assets when what we want them to be is homes.