The difficulty is in deciding what needs to "stop". Do you "stop" rent payments when those businesses aren't allowed to operate? If yes, do you "stop" loan payments for landlords who depend on rent to repay loans? What about landlords who only half depend on rent for loan payments?

This is why it's an economic problem - it's easy enough to determine which physical activities need to stop to reduce disease spread. It's much much much harder to untangle the interrelated economic activity and decide where pauses should be made. There isn't a clear delineation between people whose economic activities are unaffected, and those who have been brought to a sudden stop.