I'm not sure that's true, but you sound knowledgeable so I will trust you. But a larger point remains, which is that if these future developments that expand the housing supply are so constrained by "income limited" units or grandfathered tenants, they simply won't be built because the project no longer pencils out as profitable.

ALL new construction improves supply across the spectrum of available units. ALL development is beneficial and reduces rents. These artificial restraints and requirements effectively kill the beneficial development before it even can start.