Yeah but technically it still would free up bitcoin as if it was loaned to you, with the risk of liquidation of the collateral you place (or stop loss targets) and the work needed to manage that risk. It's like how investors use LEAPS to get exposure to a stock over a year or more without actually putting all of their collateral into the equivalent amount of equity for the same price fluctuation. That frees up more collateral to be used anywhere else because of the fungibility of money. So technically, it's the same, just with highly adjustable risk and risk management requirements.