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.