Even if rents were capped at half what a mortgage for the same property is, you still are in a position that once the asset of the house is paid off the landlord now has an asset that earns income without labour.
And the inverse.
Regardless of what you earn (to a point, even into higher income brackets), if you do not put it into an asset that can house you, and you stop earning, you cannot live without reducing your overall capital.
So rental means a lack of opportunity to reduce your labour dependent income over time (important as you age), and a reduced ability to weather negative life events.
A separate concern is who should receive the money and how we morally justify that, since they didn't produce anything or work to earn it.
I've seen many parents and grandparents of friends having to live on scraps and decide between healthcare and rent because they just can't make ends meet anymore.
For the young folks that can't buy because they can't save its even worse, they'll be indentured servants for as long as they're useful for the labor force and will then be thrown into the bin.
I suppose if it comes to that, I'll find a way to sacrifice my then-worthless life for the greater good. And it will be sad, but important.