~snip~
Any idiot can print numbers, and then claim they are coins, without having any liability to redeem them. That's called a fraud and not a payment system.
Bitcoin uses proof of work to generate new coins. In your terms, this would be the liability to redeem the coins. Miners are constantly working trying to find a new block, if one finds a new block, bitcoin is redeemed to the miner who discovered it.
Without work, there's no generation of new coins. You need the work to generate the coins, it's literally what you're saying. There is a liability, the work needs to be done. Bitcoins are not created out of thin air, they are given for work done.