> Housing asset prices are primarily constrained by the affordability of rent
In a low interest rate environment this is not really true. Speculative booms can and do occur (see Australia). During such booms the ratio of house prices to rents diverges significantly. It is rents that are constrained by wages - not house prices (people don't take out loans to pay rent like they do to buy houses).
Sure, there are transient booms and busts. But as you imply, those are exceptions. Long term, apartment rents are constrained by wages and likewise monthly payments on mortgages are constrained by wages. Those monthly payments are directly related to interest rate and total asset price.
In a low interest rate environment this is not really true. Speculative booms can and do occur (see Australia). During such booms the ratio of house prices to rents diverges significantly. It is rents that are constrained by wages - not house prices (people don't take out loans to pay rent like they do to buy houses).