On the other hand, real money often has restrictions on the ability to take on leverage in the way that a bank doesn’t. Real money can often be constrained in their ability to arbitrage the basis because their mandate doesn’t allow them to. In my experience, one of the fundamental laws of finance is to never underestimate mandate constraints.
Finally, and most importantly, central clearing allows for the multilateral netting of exposures so that a given level of risk protection can be achieved with a smaller amount of collateral, or vice versa, a given amount of collateral can achieve a higher level of risk protection.