It is. It is inhumane.
I agree with you that policies which artificially constrain the supply bear much of the blame, but an outcome can be inhumane in and of itself, even if it emerges from "supply and demand".
People getting thrown out of their homes because the value of their labor no longer covers the cost of their dwelling is bad.
Sure demanding people to leave the place they are used to live in isn't the nicest thing to do. But it can be done in a reasonable way, e.g. with a plenty of warning ahead of time.
(Disclaimer: I was asked to leave a rented apartment twice, not in SF; both times I was told so just a month ahead of time.)
That isn't an argument.
Someone having to rent a smaller apartment in a less desirable neighborhood is not inhumane.
SF has far more housing demand than it has housing supply. The pie is a fixed size. Policy can pick and choose the winners this way or that way. Either way you have the same number of winners and same number of losers. All you're doing is arguing over who you think should win and who you think should lose. The net amount of "inhumanity" is the same.
Maybe in your preferred policy the people who were there first get to be the winners. Good for them, I guess. You picked one winner. But there's 5 losers who are denied access to economic opportunity because they didn't rent someone else's home 15 years ago. That's inhumane if you ask me.
SF is one of the most desirable places to live in the entire world. Not everyone gets to live there. There's no universe in which everyone gets to live there. If we lived in a fantasy Star Trek future with no money then even still not everyone who wants to live in SF would get to. The fact that not everyone can live in a highly desirable location is not inhumane. Someone living there and then later having to live somewhere else is not inhumane.
If we want housing to be an investment, we have to acknowledge it's going to rise in value faster than inflation (otherwise it's a crap investment), which means it won't be affordable.
Conversely, if we want housing to be affordable, it cannot rise in value faster than inflation, which means it can't be a good investment.
As Charles Marohn says, it's not even a "problem", in that problems have solutions. It's a predicament.
That seems to be the problem at its core.
Also housing can't rise faster in value than inflation long term. It can for a while but eventually it'll reach a point where even with a 30 year loan you can't purchase it with any job in the area where the house is located.
So if housing is fundamentally unsuited for gaining wealth in the long term for anyone but the wealthy and if it's core function is to house people, then I don't see a need for housing cost to appreciate above inflation.