The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned. But neither the United States nor any State shall assume or pay any debt or obligation incurred in aid of insurrection or rebellion against the United States, or any claim for the loss or emancipation of any slave; but all such debts, obligations and claims shall be held illegal and void.
Since most of you readers know where my sympathies lie I won't bore you with that. The Article seems pretty clear to me, the debts incurred by the US are its debts and won't be questioned. It doesn't seem in the least odd to me that debts incurred by the US are its debts and the US is responsible for them as legally entered into contracts and must be honored. That, in itself, is the reason why most think it would be catastrophic to default on that debt and it is the reason people are willing to let the US assume debt. Whatever it is that you think about government spending, that spending has been done on the authority of the citizenry of the US whatever their political leanings.
Setting a budget is certainly the business of the Congress, primarily the House, but obligations are not subject to political high-jinks. It is not the business of Congress to hold hostage the debt and obligations of the United States for any reason. There is a difference that seems to have evaded the Congress of the US.
and a few others...