Remove the carveouts against money laundering for real estate, the preferential tax treatment / mortgage interest deductibility for investment properties, things like that.
Why should airlines or manufacturers or other businesses be able to deduct the interest on their loans, while one specific sector cannot?
I want to make a distinction between productive use of capital and rent-seeking. If you're getting a loan in order to buy an existing piece of property and rent it out - that is not productive, it is rent seeking (since you generate cash flow from just holding onto an asset and not doing anything with it).
If you're building a new house or renovating/repairing the existing house with that loan, then the part that goes towards building/renovation is productive and the interest on that part of the loan should be deductible.
The point is that people can make a lot of money by buying up real estate "portfolios" and simply sitting on them to generate cashflow, pricing others who want to buy a home out of the market. This would even out the balance a bit and make holding onto lots of investment assets more expensive but buying your first home [relatively] more affordable.