I live in Sweden and I can attest that rent control is a disaster. Lofty political aspirations aside the simple truth is that the middle class does not want to live in the crime-ridden suburbs and will do anything to stay out of there. As that is the only place where you can rent they're forced into taking huge loans and buying something in the city, or they can try their luck on the unsurprisingly flourishing black market. The effect of this is that Sweden now has one of the highest private debt burdens in the world. As long as the prices keep going up the system keeps limping along, but if that would ever change there could be some interesting consequences.