Well, I'd say there are two main factors regarding tourism difficulties in Barcelona:
1st: Rental and purchase price increases as you said, somekind related to the Airbnb rise in the city. (check http://www.dwarshuis.com/various/airbnb/barcelona/ and https://translate.google.es/translate?sl=ca&tl=en&js=y&prev=_t&hl=es&ie=UTF-8&u=https%3A%2F%2Fwww.ara.cat%2Feconomia%2Fpreu-dels-pisos-dispara_0_1714628570.html&edit-text=&act=url)
2nd: Some people asks for a more cooresponsive and integrated tourism by reducing the access of cheap tourism in the city and searching for formulas to stimulate a tourism interested in the people and culture of Barcelona.
Anyway Valencia is also beautiful and its people is wonderful too. :)
RE: 12 destinations travelers might want to avoid in 2018--Espagne