I don't think it requires warehousing. Any underpriced (non-cartel) units are going to be held onto by the current renter because the available market is too e

I don't think it requires warehousing. Any underpriced (non-cartel) units are going to be held onto by the current renter because the available market is too expensive to move. But the renters being forced to the market by rent increases aren't finding cheaper places so they're paying higher rents. Presumably any new construction is going to be in the cartel.