This is totally just a guess, but maybe it justifies the labor they paid for to build new homes. The city spent a lot of CCP dollars to build a big city, but the new homes are sitting empty which looks really bad for the statistics/metrics the local government gets measured on by the CCP. So if they show that the new homes are being bought, then they are able to justify all the money they spent.
Or it could be a way to hide a kickback to a developer.
Or maybe it is a way to get people to change the way they think about buying/selling/moving. If people are used to just staying in the same house for their whole lives, then you only need new houses if you have a growing population. If you need to pay laborers to build “something” to keep them employed (make work), then getting people more comfortable with buying a new house and selling their old house (that probably gets flipped or demolished) allows you to justify building new houses, plus a market for paying people to demolish, plus a market for paying people to be realtors. State-owned labor markets can get weird and don’t always make sense.