When a bunch of people decide to be deadbeats and welsh on their debts all at once, they hand losses to their lenders. This erodes their lender's capital and their ability to make any new loans. It makes financial capital scarcer, objectively. It also increases the perceived risks to making any sort of loan, especially those similar to the ones experiencing high losses, but also just to all of them, since financial capital is fungible and flows to higher bidders and better credits first, when it is scarce.
This automatically raises the rates that everyone has to pay to borrow capital. Regardless of what authorities try to do to make capital cheaper or to keep interest rates low. Less capital existing to serve a market in which higher risks exist, loan rates must rise. Since the authorities are trying to keep rates low, this occurs as a vast increase in the spreads between the highest quality credits and lower credit tiers, rather than as a parallel shift higher for all interest rates. But it happens. The Fed can send rates to zero, but the only people who get access to borrowings at those near zero rates, are the government and government-guaranteed banks and other underwritten financial institutions. All the actual borrowers have to pay more, a lot more. Vastly wider spreads than before the deadbeat epidemic.
You can't make capital cheaper by refusing to pay for it.
You make it more expensive instead.
The only way to make capital truly cheaper again for the end borrower, is to fill the financial coffers again, to restore loan capital, to replace the losses financiers already experienced, and to attract new replacement capital by offering higher rates and actually delivering on them, through better repayment experience, as well. This takes time and it is intensely painful for anyone reliant on financing during the wide-spread period, but it must occur. The only way to have cheap capital again is to have fat and happy capitalists.
Until every penny of it is repaid, everyone sweats harder for every scrape of capital they use. This economizes on its uses and also tends to encourage higher savings that gradually reconstitutes finance capital. As people tend to be risk-averse after past losses, they pile into safe forms of investment - treasuries, guaranteed bank CDs - and their mutual fear makes them do so even at rates near zero. This means they are providing more and more loan capital to intermediaries at lower costs, at the very moment anyone willing to run banker-style risks can charge wide spreads to lend it out again to riskier places.
Everyone trying to stiff financiers is inherently self defeating. Just like trying to stiff bread providers in a famine, it can only drive prices higher still.
More like people whose job it is to provide bread, but who don't have any flour because they lost it in a craps game.