It's a short term authoritarian bandaid that doesn't even help that many people, all the while fostering resentment and opening up increasingly authoritarian measures in the future. We should go the asian route of increasing density and size. It's not like Barcelona is fully developed border to border.
Barcelona has a 16,000 people per square km density - that’s already one of the highest in Europe. https://worldpopulationreview.com/world-cities/barcelona-pop... .
Nor does it mean this trade off for a measly 10,000 flats is worth it in such a large city.