Programmers pervasively underestimate the sheer amount of manual brunt work that business users routinely do by hand and with their own eyes, mouse, and keyboard to make spreadsheet-based processes "work out."

I work in Finance. It's routine for the folks I work adjacent to to spend literal hours performing a task using a spreadsheet. The same logic could be executed by a query engine or scripting language in seconds. But... I know from trying... it would take months if not years to accurately identify and account for all the weird exceptions and edge cases that the human operator is accounting for intuitively because of their undocumented tacit knowledge of the domain.

So while the spreadsheet itself as an artifact is a mess, and the process as a whole is gallingly inefficient... the outputs they produce are often preternaturally correct.