Bonds are the mechanism by which the government issues new money. They cannot “print money” without selling the equivalent value in bonds.

I knew that’s what you meant but I don’t think that’s true. They choose not to because there’s concerns about inflation and devaluing the dollar, but there’s no constitutional restriction on that. The necessary and proper clause is pretty broad, as is Article I, Section 8, Clause 1.

I’m not a lawyer though