I work in finance and we have prod excel spreadsheets. Those spreadsheets are versioned like code artifacts, with automated testing and everything. Converting them to real applications is a major part of the work the technology division does.
They usually happen because some new and exciting line of business is started by a small team as a POC. Those teams don't get full technology backing, it would slow down the early iteration and cost a lot of money for an idea that may not be lucrative. Eventually they make a lot of money and by then risk controls are basically requiring them to document every single change they make in excel. This eventually sucks enough that they complain and get a tech team to convert the spreadsheet.
My experience being they are an exception rather than the rule and many more businesses have sheets that tend further toward Heath Robinson than would be admitted in public.
They usually happen because some new and exciting line of business is started by a small team as a POC. Those teams don't get full technology backing, it would slow down the early iteration and cost a lot of money for an idea that may not be lucrative. Eventually they make a lot of money and by then risk controls are basically requiring them to document every single change they make in excel. This eventually sucks enough that they complain and get a tech team to convert the spreadsheet.