Exactly what I was trying to say!Competition is indeed central to a free market. The clue is in the "free" part where a market is free to rise and fall due to the constituent parts of the market. This is basic law of economics supply rises to meet demand.
Herein is where we have the issue, the market is not "free" as Govt interference is distorting the market. In a normal functioning "free" market suppliers would come and go based on the attractiveness of the trading environment within that market. As the trading environment is becoming so anti landlord this is one of the reasons more landlords are leaving rather than entering it.