Absolute numbers create bounds. USD can’t drop to 1/100th of it’s current value without huge shifts as people would need to pay 100x as many USD in taxes driving up demand for USD. Now, their is slack in the system, but that’s a good thing as it provides price signals and feedback loops.

Even record setting sustained inflation of say 2% per month in the middle of some horrific economic issues would still be a bastion of stability relative to many currency’s throughout history. So, as long as the economy stays steady and the USG does not do something monumentally stupid the US economy really does back the USD.