OK, but why do you think there's a lack of rental properties?
Because people can't afford to buy, so everyone's renting.
And why can't people afford to buy?
Because they're wasting all their money on rent, which is going up and up, and they can't save for a deposit/ mortgage.
That rent is often going to landlords who own multiple properties and are making a tidy profit from it.
If people owned fewer properties and were not putting so many out on the rental market, but instead those properties were available to buy, the price of properties to buy would drop, and people would be more able to afford them.
Everyone should be able to afford to buy one home to live in.
Whilst that is not the case, people should not be able to buy up multiple homes and charging people extortionate rent to live in them.