>"It's also interesting that people genuinely believe this is going to solve the problem rather than exacerbate it."
No, nobody believes that this one action is going to solve a housing problem, where did you get that from in the article? The point is that Berlin took a pro-resident stance here which is both encouraging and unusual in the current "developer takes all" policies that many other desirable cities around the world have adopted. Berlin also enacted legislation restricting AirBnB rentals in the city. They understand there is a housing problem and are at least taking actions to address the concerns of the residents and possibly buy some time.
>"The only solution to this "problem" is to let people build additional housing to increase supply."
What do you suggest, Berlin gets rid of parks and public spaces and allows high high rise condos to occupy that space instead? Part of the quality of life and charm of Berlin is those spaces. Also there is nothing in this article that suggests that the potential buyers were going to increase the housing supply. Housing is a pretty complex issue and your completely reductionist policy suggestion is absurd and naive.
>"And yes this will occur even if it's made "illegal" to sublet these apartments (this exact situation exists in NYC with people who have rent controlled apartments and people still do it all the time)."
This is completely untrue. Firstly there are barely any "rent controlled" apartments left in NYC. They are an endangered species and this idea that people who don't live there are subletting them out at a profit is a complete myth. See the following:
https://citylimits.org/2015/03/09/nycs-endangered-species-a-...
As of 6 years ago rent controlled apartment in NYC were 1.8% of the total stock. And there are significantly less now:
https://en.wikipedia.org/wiki/Rent_control_in_New_York