> where you are trying to catch the difference between SUM(A3:A12) and SUM(A3:A10) in a thousand different cells.

Excel does a pretty good job in highlighting which cells are selected when you edit a formula, and it does a pretty good job of maintaining the meaning of the formula under sheet transformations. For example, if you inserted a row between rows 8 and 9 then the two formulae would be =SUM(A3:A13) and =SUM(A3:A11) respectively.

This may have been a genuine error, but the two researchers definitely started the process with a goal in mind, and when the results agreed with their goals they didn't bother to check.