Couldn't say it better @Michael Baum.
They don't seem to realize that Barcelona is a world city and that in world cities prices for living in the center go up. Same for Amsterdam, New York, or any big city in the world.
And I doubt taking out around 10.000 tourist apartments will bring down real estate prices because it hasn't been going down since they stopped giving more licenses a couple of years ago. Again because of the same reason.
The real problem is that more (social/medium priced) housing is needed which the local government hasn't been investing in for the last 1/2 governing period. Their tendency has been to limit activities instead of increasing stock. Madrid has been doing this a lot better for example (the difference between a left and a more right business-oriented governing body in charge).
It is also important to accept that living in the center of a big city is getting more expensive and that, for the same price, with time it is only possible to live in the 2nd/3rd tier neighbourhoods.
The economy never stands still and you can not go against it. Even with these limitations.