This is cart before horse stuff. As noticed by other commenters some people need to rent. I am blaming 'quantitative easing'. If the central bank buys a whole lot of assets where do other investors go?
Also, it's no longer always a full write off, it's a write off at a capped rate. Those with low incomes have a full write off, those with high incomes see a more limited effect.
It is tax deductable, so you are taxed less, typically max 50% of the interest sum.
It can be a misleading to say this means only 50% or 37% of your interest can be deducted. It could still be fully deducted. i.e. if your income is taxed at 37% rate, then the 37% rate of 2023 will mean your entire interest can be deducted from your income (100% interest deduction).
It means that at higher progressive tax rates for higher incomes, e.g. at 50%, only 37% of the 50% can be deducted.