The larger context is Spain’s population is flat with declines in the last 24 months and trend likely to continue in the coming decades. Barcelona’s population peaked in 1979 and only recently recovered to the level seen in 1990. So they likely don’t actually need to add significant housing long term. Freeing up AirBnB apartments in the short term looks like a reasonable solution until population decline kicks in and removes the need for extra housing.
https://datacommons.org/place/wikidataId/Q1492?utm_medium=ex...