Well a few scenarios come to mind - 1) keeping the test data up-to-date as the schema changes takes a fair amount of work, especially if it's a schema that's ac

Well a few scenarios come to mind - 1) keeping the test data up-to-date as the schema changes takes a fair amount of work, especially if it's a schema that's actively changing and being worked on in a team by more than one developer. 2) Not everyone wants to necessarily craft their own test data even if they can, because well they would rather spend their time doing something else. 3) test data generation at even modest scale can be quite painful to hand-craft (and keep up-to-date). 4) capturing all the variances across the data e.g. combinations of nulls across fields, lengths of data across the fields, etc.