This would be helped immensely by the city charging a vacancy tax on property owners. DC charges a 5% tax rate for vacant buildings, and a whopping 10% tax on blighted buildings.

Baltimore charges the exact same rate to property owners regardless of the status or condition of the building. If Baltimore adopted a similar policy to DC, it would force these loser property owners (many of them out of state) sitting on vacant blighted buildings to sell to people who are willing to do something with them.