That those airbnb many people get are kicking out the families off their neighborhoods, that tourists are being the priority instead of the citizens, that that type of economy is just erasing local businesses -created for daily life and not for a weekend holidays-, that it's degrading the quality of life of those who live there... Las Ramblas were once a place for the people of the city. Most of young people now can't name a single spot there that is useful there for someone who lives in Barcelona. I could continue but if you try to look at the future seeing what happened in the last 10-15 years, you can see Barcelona turning into a theme park instead of a city. Being controlled by external economy does no good to anybody anywhere, and that's why you can read "tourists fuck off" in some walls. If you travel you should be aware of the type of tourism you're going to practice and the consequences for the area you're visiting.