Because that implies more supply and landlords are happy with the supply being restricted. The people that has the money to build won't, the government will follow the money, so the state doesn't help. That kind of question reeks to "why are you poor?", well, because I have no money!
I don't think there is, really, but plenty of potential housing (and also the cost of construction) is pressured by "pseudo-housing" (Airbnb, vacation apartments, boutique hotels), often fueled by foreign capital.