There’s someone in this thread arguing exactly for squatters right for another’s primary residence, barring their ability to organize some kind self defense. Didn’t sound great
Generally, most people aren't so extreme as to say private ownership shouldn't exist at all. At least from most of the people I interact with here in Barcelona.
Besides what people think is right/wrong, the police does help you (quickly) to throw out people that try to invade your residence that you actively live in.