It's the difference between double entry bookkeeping and single entry bookkeeping.
By providing a common ledger that can be used when you desire single entry bookkeeping you don't necessarily need all the backchecking as you're using a smart contract to ensure upfront that when the money is settled the assets move.
By providing a common ledger that can be used when you desire single entry bookkeeping you don't necessarily need all the backchecking as you're using a smart contract to ensure upfront that when the money is settled the assets move.