First is to keep workers out of state unemployment insurance programs. These differ per state, but are often deliberately miserly and/or burdensome so that they motivate recipients to go find a new job. But we don't want the unemployed to hit the bricks. Payroll support is then a more easily-administered form of federal UI. (Plus state UI is written in COBOL, they will literally crash.)
Also, retaining workers will help to ensure a V-shaped economic recovery. Once the health crisis ends, retained workers can just go back to work. But layoffs followed by rehires means more retraining (not retaining), and a slower recovery.
The point is that we literally cannot pinch pennies now: anything we "save" will hit us twice as hard as a new entitlement cost, or a cost to the states, or in reduced tax revenue, or whatnot.
Money is a fiction; the real risk is mouldering factories and disused skills. If a year from now the US is trillions more in debt, and prices are 2% higher, YET we are healthy and working and productive, we will have been successful in countering the health and economic crisis. We should be so lucky.