And zoning and giving landlords great benefits (some countries not taxing wins from rents, others allowing changing rent easily, etc.) really solved the problem? Multiple major countries (in which rent control is not a thing) have huge housing issues, so something should be done. For some places I would much prefer reducing regulation required for new constructions, but this is very situation dependant.

Rent control working depends on multiple other policies and on the characteristics of the place. For Paris for example it did seem to have a positive effect: https://hal.inrae.fr/hal-05315123v1/file/Morin%20et%20al.%20...

Why does this might not apply to other cases? Paris is very dense already, not a lot of places to build anyhow. What other policies are required? Ensure people do not buy only for investment and leave things empty - they raised the uninhabited tax to discourage that, will see if enough to make a dent.

Also in countries where rent control is a thing. About 20 years ago the government decided it was "good enough" and stopped nationally planned housing projects (which resulted in decentralized planning and mostly expensive, high profit, housing being build), 'motivated' the market by providing tax breaks (giving higher profit and less investment in non-controlled renting) and as a bonus taxed the subsidized housing market a flat rate on top (result: hardly any new construction or investment in subsidized housing).

Almost all measures since have been detrimental to new housing, great for real estate owners, extremely poor for renters and allowed house prices to skyrocket. None of these things are on their own and it's a more-or-less global thing but they've done a great job making it worse.

And as a bonus: this was projected to happen by the governmental planning agency and rejected as fearmongering.