Still wrong:

1) Apartments get converted to condos, or re-purposed because the property has value, but renting doesn't.

2) The population keeps growing meaning that your same number of units don't meet the needs.

3) Rental supply also drops as people opt not to move and sit on their rent-controlled apartments, limiting the supply for those looking.

This is why rent-control has the effect of making housing worse, even if the rental supply is maintained.