That's how housing costs can increase faster than the income of an area, it's the market displacing those with lower incomes, and readjusting to only house the wealthiest.
Add in that housing prices are distinct from the housing costs, and that leases only change rent occasionally, and lots of people are owners and have fixed costs, and prices can rise quite a bit faster than incomes.
And new home construction is at an all time high.
Scarcity of inventory is not at all the same thing as scarcity of housing. This has been a powerful narrative in driving FOMO buyers though.
Your chart is the number of units under construction, but that high number doesn't translate into more new homes than ever before, because completions have been massively delayed. So there's a lot of homes sitting half finished as they wait for supply chain crunch's to resolve. And to compare this to numbers from the 80s means normalizing for length of construction, something which is getting delayed more and more.
Overall, construction has massively constructed since 2008, and even before that it had been trending down for a long time.
I suppose it makes sense. They say not to spend more than 1/4 (or 1/3) of your income on housing but if a house costs 2/5 of your income you're probably not going to set up a tent and wait for interest rates to come down.
Housing costs tend toward people's ability to pay, otherwise folks default. That's why the banks ask you about your income and credit worthiness, they want to know you'll be able to pay the mortgage and not default. If money costs increase faster than income, folks won't be able to afford as much money (as high a price).