I'm a bit confused, this article seems to only look in depth at rent control in San Francisco? San Francisco and any city in California is a major anomaly compared to other cities in the world. For example, rent control in Montreal works fairly well for renters and has kept the city affordable for the middle class while residential construction still booms.
Thanks, I hadn't realised that obviously existing landlords might stop renting out a place, which would reduce supply of housing - that could be problematic.
It also mentions that apartments got transformed into condos. This might be a problem with my not being a native speaker, but: if one apartment is turned into multiple condos, isn't it able to house more people? (Though being "new" housing, I suppose they'd then be able to ask higher rents again?)
Since there's already some effort to confiscate property that's been empty for too long, I doubt too many landladies in Berlin will dare to go that route.