Sorry, several generally means two, but I apologize if that made it sound like more, hehe. But you're 100% right, many more studies are needed after a longer period to see the long term effects.

But I think the main idea was that more and varying interventions are needed to lower the cost of housing (such as building affordable rentals) Its a complex and ingrained problem, and a single step like eliminating investors in such an inflated market is still not going to benefit low income people, and may in fact backfire. But at least other regions can learn from it in their approach.