> once I have acquired dollars and wish to send them to you I must involve a third party

Cash.

(There is no way to send electronic dollars without involving a third party, though more money is laundered using dollars and euros than cryptocurrencies. I'd argue leaving a permanent, public record of transactions is a poor price to pay for decentralized electronic transmission, particularly given the centralized issuer and guarantor problem.)

>once I have acquired dollars and wish to send them to you I must involve a third party.

Isn’t that the same as bitcoin and every other cryptocurrency? You need a cryptowallet (third party); a device (third party); and internet access (third party).

stablecoins achieve many of the original goals of bitcoin, but not any of the most important goals. the important goals are censorship resistance, and fixed monetary policy. Nothing in the crypto space addresses these goals better than Bitcoin.