...debt repayment subtracts from growth as people defer or forgo consumption to pay down debt.

Obviously this is true, but hardly the reason for the recession now or housing market crash. The debt first creates debt deflation to real economy, and only after that, problems start. All happens before deleveraging. I'm quite sure that USA, Ireland or Spain were not deleveraging when problems started. The Serious People talked about "liquidity" (whatever that in the end means(most likely a recession of the real economy)).