Its possible to create a mapping without source qualifier.
As you know, mapplet is used for multiple occurrence of the same logic. Normally we use the mapplets within the flow of mapping. But, if you are using mapplet as a source then it may be loading the different set of data into different tables.
By the way, is this mapplet used only in one mapping or in different mappings. if its used in different mapping is it loading the different data sets based on the conditions