These views are those of an older homeowner that doesn't consider themselves a land owner, but as more of California becomes renters and are locked our of owning land by that cabal, the contradictions of these viewpoints will become increasingly untenable as their inherent unfairness continues to exploit people with less wealth.
For example:
> with the most recent passage of the rent control legislation in CA (benefiting developers).
This doesn't benefit or harm developers at all, it just limited the economic rents that wealthy people can extract from the less wealthy. Demonization of developers may be able to persist for a while, but landowners and homeowners are clearly the culprits of wealth inequality here and the developer blame game won't last much longer. For example, take a look at this recent NYT opinion article, which shows the sea-change of opinion about who is to blame for housing:
https://www.nytimes.com/2020/05/11/opinion/coronavirus-us-ci...
> If anything, upzoning always increases land prices as it allows more economic value to be extracted from it (think how big the cash flow would be from a 20 unit apartment building developed on a 10000 sq ft lot compared do a duplex even assuming that per-unit rent goes down).
That "always" is completely wrong, which is evidenced by basically everywhere else in the world that has enacted fairer zoning schemes and achieved far better housing results.
Upzoning only vastly increases land values where there has been massive downzoning, which creates massive market pressures in the few places that allow tiny amounts of upzoning. This combination of downzoning wealthy neighborhoods then doing targeted upzoning of lower income neighborhoods has resulted in massive destruction of the few places that were affordable. But policy makers are getting wise to the wealthy people saying NIMBY; future upzonings will increasingly require affordable housing in wealthy neighborhoods, or there will be massive city- or state-wide upzonings as in Oregon or Minneapolis.
The playbook of the wealthy white suburbs has been shown to be disastrous for society, and the next generation of planners, seeing an entire generation locked out of the chance at building homes, is increasingly rejecting the disastrous arguments you put forward. Society can not survive another 20 years of what has happened to housing, which is the disastrous effects of homeowners saying NIMBY to any newcomers. Exclusion of that sort is creating both economic inequality and massive societal disruption (except for the homevoters who directly benefit from this while slyly claiming that they don't care about property values, just about excluding any new people and preventing change.)