Housing is the major wealth store for the middle and lower class. Most in the middle and lower class will spend major portions of their income on this for many years of their life.
If supply goes up, then the middle and lower class loses significant amounts of their wealth immediately since buyers have more options. If supply goes down or fails to keep up, then housing becomes increasingly unaffordable and the wealth of people who already own goes up.
What's best for society is if everyone who's wealth is tied up in property takes a hit to their wealth so that housing becomes affordable and loses it's status as primary wealth store, but that would be devastating in the short term to the middle class and therefore completely politically untenable.
So because housing policy discussion takes place under these conditions, it's nearly impossible to have a reality based discussion because almost everybody loses except societies richest.
"Housing can either be an investment or affordable."
Almost everyone in any position of power or with institutional reputation has an extremely vested interest in both keeping the broken status quo and convincing people that absolutely anything other then basic economic theory of supply and demand is chiefly responsible for housing prices.