But we have stablecoins, like USDC, to act as on-chain dollars. The point is in a world of very robust decentralized exchanges, it's easy to buy tokens with dol

But we have stablecoins, like USDC, to act as on-chain dollars. The point is in a world of very robust decentralized exchanges, it's easy to buy tokens with dollars (or vice versa), by sending dollars from your bank account to Circle, who will send USDC to your wallet, which will then buy the token of your choice from a decentralized exchange. In this context Circle is still a centralized party that's necessary to interact with the off-chain banking world. But Circle has much less room for chicanery than a traditional centralized exchange. There's no opportunity to front-run, insider trade, liquidate your customers or anything else that OP brought up in the context of centralized exchanges, because all Circle is doing is filling the very simple task of converting 1.00 USD to 1.00 USDC and nothing else.