Spreadsheets represent unknown risks in the form of errors, privacy violations, trade secrets, and compliance violations. Research on “Cognitive load,” the amount of mental effort required for a task, shows that building complex spreadsheets demands as much concentration as a GP making a diagnosis. Equipping users with the knowledge and skills to build robust and accurate spreadsheets could help them identify and avoid pitfalls.

Source: We keep making the same mistakes with spreadsheets, despite bad consequences

Spreadsheets are software engineering without rigor. Great, up until a point.