I don't think this an example of YIMBYism, as nothing new has been built, but it is an example of how destructive rent controls are.
The article cites two major reforms leading to the improvements, but both are mostly the result of the owner and the occupant being free to enter into whatever contract they wish with each other:
The owner and occupant get to determine the lease term, which were previously subject to forced multiyear terms (at least, implicitly ... the article doesn't say what it was like before).
The owner and occupant get to determine the rental price and terms for price adjustment based on inflation, independent of the government's price indexes that were mandatory before.
I mostly, somewhat comically but also genuinely, resent YIMBYism being a blanket term for housing reform. No one is really a YIMBY but that's why the term is so effective because it's a lie about self-sacrifice - we all viscerally oppose people building in our backyards, but not in other people's backyards so we bluff like this. Incentives-wise it's shaped a lot like "yes, tax me more uncle sam."
YIMBY is only a thing because our housing property rights are subject to politicization.