A policy like this would apply to the entire market. All landlords have vacancies at least occasionally, due to renovations or bad luck.
It won't affect a tenant's ability to pay more, but a policy that increases ownership costs across the board means that there won't be cheaper alternatives in the competition, so the tenant will need to either find a way to pay the increase or they'll have to leave to a cheaper market. The highest rent the market can bear will go up if it's not possible to compete any further on lower prices.