More homes means either building on new land or adding density to existing land. There isn't much "new" land available in SF, but knocking down existing buildings is still very risky. Even if your proposed development meets every existing zoning regulation, it can be shot down.
So "more zoning control" here means putting more control in the actual zoning regulations, as opposed to allowing anyone to try and stop the process via ballot measure or legal challenge.
Increasing supply (building more or denser housing) will naturally decrease prices, which is where the investment bit comes in.
The phrase "more zoning control" sounds like increasing the amount and complexity of zoning regulations, rather than, as you suggest, removing unwritten rules.
"Make the re-zoning process more predictable" would maybe be a better slogan.
They're saying almost exactly the opposite of that - establish clear rules that, if followed by developers, lead to automatic approval, rather than the current mess of endless, case-by-case approval processes.
> "stop treating homes as investments"
This is specifically deaing with government policies that prioritize houses' utility as investments over their utility as consumer goods - eg by restricting supply.
Zoning control != zoning restriction. Control over zoning can mean things like mixed use, autonomy at the lower levels (versus "our hands are tied by group X" situations), and issuing permits on a "default yes barring interrupts" basis, instead of a "default no pending complex approvals".
Treating homes as investments is what leads to most NIMBY ways of thinking, which while harmful to the region at large, make perfect sense on a homeowner level. Many SF land owners have bought in at overvalued levels and continue to pay or receive overvalued rents. Motions that would make the city more affordable on the whole threaten the size of their returns, so people who treat homes as investments are often in direct opposition to what would be good for the less rich.
TL;DR the 3 pieces you mention can coexist as "more homes, of more varieties, regardless of the fact that will threaten existing homeowners' ROI"
This is something that puzzle me. If areas are upzoned and higher-density redevelopment becomes possible, then housing prices will drop. But housing prices aren't the same thing at all as land value. If I owned a small low-density unit on a small plot of land, I wouldn't be able to sell the house as such to someone who wanted to live in it for as much money, but I think the value if the property could redeveloped as-of-right at higher density would increase.
So at least some plots of land should increase in value.
These demands are not very well scoped.