They taxes vacancies so vacancies went down - but that doesn’t mean that someone who was happy keeping their property empty put it on the market and found some random tenants with all of the hassles that entails - you can never get rid of them as the laws strongly favour tenants. So you lose control of your “property”

Instead they find someone in their network, like a friend or friends adult child that is studying who can stay there and they pay a trivial rent to “take care of the house”