Rent control simply locks in a set of winners when it is implemented (which for the most part stays static and doesn’t apply to new demand), the government then has to promise that rent control won’t be implemented on new supply so developers, businesses, and private landlords just don’t give up on the rental market completely.

I don’t see rent control as very useful, but I doubt it is very relevant to the current housing shortages throughout the cities that have it either (given that the same problems apply to cites that don’t have it).