One thing that tends to be excluded in most analysis of rent control is the preference of landlords to operate fewer, more expensive units. When you have more units, you have more to keep track of - more tenants, more staff, more maintenance. A high-end luxury unit and a dirty fleabag mostly differ in some move-in amenities and services; rich tenants might demand more, but they don't trash the place
faster. So every unit tends to be luxury by default since that's where the upside is.
If your rent increase gets capped by rent control, your ability to stay at a limited scale of operation and just add to the price gets squeezed, and that motivates making more capital investments in property(and specifically in vertical upgrades, since horizontal expansion puts them in a land bidding war). It hits investment properties run by large companies the most, and challenges them to use land more effectively to stay competitive, in the same way that higher minimum wage challenges companies to use labor more effectively.
However, we still need an SB50 or successor bill to deal with the build restrictions. The landlords and developers can demand building big(and they do already in many cases) but they're held back by zoning laws put in place by NIMBY residents. The trick is that instituting rent control does something change the outlook of the NIMBYs too, since their property value has a relationship to the value of rentals. Rental rates and turnover slow down = property values slow down = their house becomes less of an investment.
So it's a good first step either way.