I worked at a large tech company that had an enormous finance department. They did everything in Excel. Our job was to automate their work. The tools we built were routinely more accurate and faster than the finance people were.

When our work was less accurate, it was because the input was bad. The input came from the finance team. The only reason they didn't disappear entirely was because they'd convinced management that there were things that the software couldn't do that only humans could futz with. The one or two percentage points their adjustments improved their results by were easily outpaced by the overall improved accuracy of the machines.