That's true in some markets, but the DOJ complaint highlights some places, like Atlanta, where vacancy rates have gone up, but rents have still climbed higher.

Why would you need to collude for higher rents with RealPage if a shortage of housing was the primary driver of rent increases?

If someone's being that greedy, they can't really use supply and demand to say their hands were tied in terms of controlling rent.

If you have the option to extract rents by forming a cartel (without legal punishment), you'll do it regardless of the underlying value of the asset you're trying to control because it's free money (assuming you can trust the other members of the cartel)