I agree, but my point was not that armchair economics is wonderful, what I tried to say was that it's often useful to find out precisely where theory and reality diverge and to focus solutions on those gaps, to avoid putting the blame on things that don't matter or suggesting regulation that won't work, like social housing (except as a short term solution), rent control or restrictions on who can buy.
I would use a formula based on the tax-assessed value of a property to set a maximum rent. Landlords should be free to reappraise their properties as often as they like to be able to raise rents at the end of a lease, but doing so will increase the tax bill as well. Call it market-adjusted rent control if you like, but there needs to be a tight range between rent and value if we want to encourage more housing starts.
