Abundance only solves scarcity if scarcity is the problem, but the actual problem is economic exclusion, which will always be able to outpace abundance because abundance has physical limits while exclusion does not.

Being charitable here (though... when called a "dunce" it's hard sometimes to want to be charitable), the statement would be perfectly correct if slightly reworded to:

"increasing supply isn't going to solve many of our problems leading to widespread homelessness and financial insecurity"

It would just help with some of them.

But that's a statement that's obvious on the face of it - cheaper housing costs buy time if you lose your job, and makes it easier to have a bigger emergency fund, but it isn't an infinite reprieve. So. The charitable interpretation still hits a wall because that would be acknowledging that supply would help with some of them, and the "dunces" nonsense suggest that they wouldn't agree even with that.

(In some states in particular, though, home ownership is uniquely protected in ways that would help fight homelessness, so increasing supply and incentivizing selling-to-an-owner vs being a landlord could be very helpful too.)

There are many reasons, one of which is certainly supply in some places, but most strongly it's just simply unrealistic that everyone will be able to make enough money to afford the mortgage on any house, let alone renting one, because of disability or age, because the housing isn't where the jobs are, because it's cheaper to import a skilled worker than it is to train one here. we do so many things that are collectively irrational that expecting one variable to unchain the free hand of the market in our lifetime seems simply... naive. And this isn't even touching broader issues about the commodification of housing and the role that real estate plays as a form of both wealth and accessible wealth extraction that make the idea of "affordable housing" downright repugnant to those who have some.

Ezra Klein is an intelligent man, but he has put his intelligence towards selling hopeful visions to professionals who want hope rather than an earnest diagnosis of the dysfunction afflicting our culture, geography, labor market, and welfare system.

I think “amount of houses” misses many important parts of how people decide where to live and what they struggle with that results in unaffordable or unavailable housing.

Where do you increase supply? The most desirable places to live like urban centers, or more likely more and wider suburbs. In a vacuum many people will say it doesn’t matter and poor people should move to where they can afford; but many people have strong connections to where they grew up and are not inclined to abandon their lifelong support systems because the pricing in one area has gone up.

How do you increase supply? Ugly 5-over-1s are cheap to make but not desirable, not particularly dense. Single family homes are even less dense. Most supply proponents are talking about these or luxury condos.

How much is the new supply? If we build new homes but they are still unattainable to the people who need them, then we didn’t help much right? Which leads me to

Who gets the new supply? Are they put on the open market for speculators/investors/landlords/private equity to gobble up or are there provisions for ensuring the housing goes to people who don’t already have housing or are physically real people not llcs etc.

Tl;dr we could build a million houses but if they are in undesirable places, unfavorable designs, or allowed to be snatched up and resold at the same high prices we already have, then supply alone wouldn’t fix unaffordability of housing across the nation.