Deregulation Caused the Housing Crisis

I suppose it is the very nature of complexity that clarity is lost. So here is a clear defense against charges that deregulation was the cause of the housing crisis.  

There are two possible causes of the housing crisis. It could be the failure of regulation, and by extension, the free market philosophy of less regulation and red tape. It also could be the interference of government in the free market system.

Here is the case against the "deregulation is the cause" case.