I think the reason the system has evolved this way is because politically it is hard for the treasury to "print" money, even though they have the legal right to

I think the reason the system has evolved this way is because politically it is hard for the treasury to "print" money, even though they have the legal right to. Having the Fed inject money into the system is a dodge, but effectively the same thing. It gets the treasury off the hook, because they can say they are "borrowing" rather than "printing" money. It's unclear to me why this bothers people so much?