I think your OP is a little disingenuous.
Just because a house is empty doesn't mean that it can be put into circulation.
Many empty houses are owned by people who have no intention of selling them.
It is well known that houses sit empty and unused, there used to be huge squatter movement in London that repossessed them.
So what do you do?
Forcibly repossess any house which has been empty longer than 1 year? 3 years?
What if the owner has had it on the market trying to sell. Should they lose the value of the house?
Should we forcibly buy any empty houses? With what money?
Honestly sounds like a police state to say that if you leave the house empty the government will take it.
Do we fine people for owning an empty house? What does that mean if the owners can't pay a fine?
And as always, the houses that sit empty because they are owned by rich investment banks/people won't mind about paying a fine, because somehow the rich never seem to pay for anything.