That seems highly reductive a definition because then a filesystem is a requirement for computation. A lot of early computing worked only in memory and results

That seems highly reductive a definition because then a filesystem is a requirement for computation. A lot of early computing worked only in memory and results were printed out on tape or via TTY. Moreover it seems like your definition of computing only makes sense as input into another computer program. Regardless many of the examples I provided do produce files. When I do finances I create spreadsheets, when I share shopping lists I'm making formatted text documents.