I explicitly talked about how the job market is affected. If your only real options are to buy or to queue for a decade, that requires you to commit to a long-term plan if you want to move to Stockholm for work.
This means you can't grab quick opportunities, you can't move to Stockholm on a whim to try your luck, so local companies and the local economy suffers. Fewer people move to Stockholm than who otherwise would, which means the city misses out on potential growth. It's an inefficient allocation of the work force on a national level.
There might be some social good to artificially restricting the growth of your most important economical urban centers, but I highly doubt it.
The supposed benefit of rent control is that attractive inner-city apartments are cheap. Sure. But since rents are based on utility value instead of location or attractiveness or market value, this means that unattractive apartments two hours from the inner city cost as much to rent as comparable ones in the inner city. It's impossible to save money by renting in a less attractive area. Normal cities have some sort of parity between cost-to-own and cost-to-rent, regardless of area. In Stockholm instead, this parity changes dramatically depending on your distance from the inner city!
Another second-order effect from rent control is that having an attractive rental apartment in Stockholm suddenly has value. This makes people reluctant to let go of an apartment once they have it, which makes them reluctant to move away to pursue other opportunities elsewhere, even if that would be the better choice. Still, if you have one, you can rent it out on the second-hand rental market, so now you've created a class of rentiers, the people that have gone through the Soviet bread-queue can now cash in on that scarcity. But I thought rent control was about fairness?