Direct cash flow to citizens gives immediate association to the source of the cash and helps restore faith in the current US economic system and government, or at least makes people a little less cranky to soften the blow.
People want change and these issues are further highlighting massive systemic problems in the US to the population at large who are already looking for significant change.
To most, a onetime $1000 (the idea that was floating, this could be different) may pay one months rent or part of it to some, but it's not going to help when it comes to layoffs and downsizing businesses are sure to follow up with. To me, the elephant in the room will be medical expenses many are sure to incur and their associated fallout that's going to be very hard to make people forget.
Make no mistake, unless everything picks back up nearly instantly (aka "when pigs fly") people will lose jobs and miss payments and be evicted and all sorts of other bad things just like in every other downturn. The point of the $1k (or whatever amount) is to buy a month for the COVID19 situation to stabilize thereby minimizing the downturn, or at least that's how it works in theory.
You could do this with the major banks and associations, but poorer Americans are already unbanked and have no available credit.
In addition, where a major component of our economy is housing and that's a major concern; there are many private landlords that depend on that income; targeting just landlords with a credit would require an entire amdministration.
One of the goals of UBI is it cuts the bureaucracy. Instead of a person or group of people deciding who benefits how, it goes to everybody indiscriminately.
I haven’t fully thought through the effects of handing out cash, just wanted to point out that suspending debts isn’t costless. Landlords would reduce spending, and banks might slip into crisis.
And what of those with no debt, but who can’t work due to virus? Or those with debt, but who can’t work? They still need to eat.