Nowhere have I said don’t bring in rent controls or better BTL regulations (in fact I support it), but you can’t do it by reducing current rents. Again, I don’t have a problem with further regulations (not allowing buy to let mortgages on new properties for example). Also, Supply and Demand hasn’t really been tried that hard now has it? We all know there is a massive house shortage. This isn’t due to BTL, it’s due to not enough housing.
But we do have issues at the moment with the amount of Buy to Let properties on the market. Decreasing rent by x% is not going to decrease the current number massively, except for those that will now default on their mortgages. Unfortunately, there are big knock on effects to this, which includes a reduction of mortgages on the market, and the regulations becoming tougher again - hence you’re then making it more difficult for people to buy these places.
Let’s not also be naive here, a lot of people who can’t afford to buy also have poor credit scores, and that holds them back in purchasing property as much as anything else.
Also, with Brexit and the uncertainty that has caused, along with low interest rates, why would someone want to invest their retirement money in this way (and for many of them it’s far too late)?