Edited: clarification
Speaking as a long-time renter who is now a property owner, I almost never think about things in terms of “limiting supply”, and as far as I can tell, my neighbors don’t either. They do care a lot about things that you’d expect a non-cartoon-villian to care about: neighborhood quality, schools, access to daylight, preservation of views, congestion, etc.
While I’m sure there are idiots out there who think like economist robots, generally, characterizing the other side of a debate as one-dimensional doesn’t do anyone any good.
HN’s average level of discourse on housing policy tends not to be particularly intelligent. Mostly folks who read the first chapter of their econ 101 textbook, then got bored.
When a city is "hot" and the working population is very transient, which is the case with SF's new tech workforce, nobody is really being a watchdog. The existing property owners will drift along, yelling about anything that might concievably affect their property values, and they get thrown bones to stay complacent since they're the most consistent voters. But they don't pay rent, and the majority of the workers still expect to be here as a career stepping stone and then move on to somewhere that doesn't suck, and so they put up with the rent and don't put down roots. People staying long-term under rent control hang onto their position for as long as they can. There's a lot of kicking cans down roads going on, hence the system trundles on.
Because if the answer isn’t 100% to both those questions, then “property owners” are not strictly the community’s constituents.