There are practical limits to the amount of debt a government can take on. Additionally, the government usually collects debt from the wealthy, who then make money back through interest payments. The "fiscal responsibility" of the Democrats is how private individuals actually extract value out of the government. Republicans issue debt, Dems use tax money to pay the interest. I think the wealthy have become more sceptical about the ability of of government to pay back these loans.
There are reasons why both parties allowed the system to remain as it was. I find it's increasingly true that new politicians don't understand the value of the systems they are meant to control. They see Chesterton's Fence and tear it down with abandon. Someone like Trump has no clue why politicians act the way they do. He lies and bullshits and does whatever he wants, and it works in the short term, but the long term effect is disastrous. These people are taking a private equity approach to government. Buy it cheap and load it up with debt, then sell as much as you can and let it crash to zero. This is more looting than governing.
There are reasons why both parties allowed the system to remain as it was. I find it's increasingly true that new politicians don't understand the value of the systems they are meant to control. They see Chesterton's Fence and tear it down with abandon. Someone like Trump has no clue why politicians act the way they do. He lies and bullshits and does whatever he wants, and it works in the short term, but the long term effect is disastrous. These people are taking a private equity approach to government. Buy it cheap and load it up with debt, then sell as much as you can and let it crash to zero. This is more looting than governing.