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.