The annoying thing is that the credit cards fully support authorizing for some amount likely to cover the transaction and using the same transaction to capture so no lingering auth sits around.
If a merchant has captured the funds and still has a hold sitting around the someone has implemented something wrong.
It would actually do next to nothing if the entire supply were vanished right now. There's about $300 billion in pennies in circulation. Around $850 per American, or roughly four days of average individual consumer spending.The economy as a whole does on the order of 10s of trillions of dollars of activity a day.Eliminating every penny would be less than a 1% reduction in liquidity, and even smaller in terms of actual use.