not op but probably because some people are so used to using spreadsheets that even if you built them a database with custom visualizations, they'd ask for spreadsheet export.
Not op but that's one of a milder example. Some management people prefer the look and feel administration to be excel-like, even able to do data modification like excel.
Some even worse that they require the data to be in excel since that's all they know.
Some even worse that they require the data to be in excel since that's all they know.