It’s not that the economy would be affected from those former employees not having the income, it’s also that the Federal agencies would be affected by the work just not getting done, or the departments being totally eliminated. For example, if national parks didn’t have the proper amount of park rangers and maintenance people, those parks wouldn’t be able to be open to the public, or vast portions of them wouldn’t be able to be open to the public.
If you have Section 8 or other federal housing programs, applications wouldn’t be able to be processed or would take way longer to process. If you file your taxes, the IRS wouldn’t be able to be so expeditious with processing the returns.
Those are just a few examples.