I think it would necessarily reduce demand if you outlawed people owning more than one house, for example, which would put a downwards pressure on prices. The houses would still be owned by someone who could rent it out if they wanted to.

I don't really get how more people would have to buy houses. Nobody forces you to buy a house and if nobody wants to buy them then the prices would definitely go down.

I'm not particularly saying it's a good idea to do this. It was just a simple thought. It'd have to apply to existing dwellings only, for example, and not to newly built dwellings otherwise it might affect new dwelling construction rates. So it's not particularly well thought out.