It's because we allow property and the homes that sit on it to be a speculative market. We encourage it. The only way for property values to be high, well, it's a supply and demand thing. If you glut the market with anything, you drive prices down. And people whose entire retirement is built on that won't be having it, let alone the conglomerate owners...
China is trying to steer into the opposite with laws against it. Not sure how well that's working, but they can acknowledge the issue at least.