Why are 600,000 waiting for apartments in Stockholm?

Good article from Economist on how rent control destroys wealth by preventing housing from moving to higher valued uses:

Rent controls are a textbook example of a well-intentioned policy that does not work. They deter the supply of good-quality rental housing. With rents capped, building new homes becomes less profitable. Even maintaining existing properties is discouraged because landlords see no return for their investment. Renters stay put in crumbling properties because controls often reset when tenants change. Who occupies housing ends up bearing little relation to who can make best use of it (ie, workers well-suited to local job opportunities). The mismatch reduces economy-wide productivity. The longer a tenant stays put, the bigger the disparity between the market rent and his payments, sharpening the incentive not to move.

... It is unrealistic to expect politicians to ignore voters’ demands. But the danger is that one abuse of power is replaced by another as renters, just like NIMBY's, campaign for regulations to lock newcomers out of the market. Although today’s residents might benefit from capped rent increases, outsiders, faced with less supply and fewer opportunities, will suffer. Just ask the 636,000 people who were queuing at the end of 2018 for a diminishing stock of rental housing in rent-controlled Stockholm. There, the average waiting-time to find a long-term tenancy is ten years and black-market rentals have begun to thrive. Rent control harms almost everyone eventually because the housing stock deteriorates.