I wouldn't recommend uploading a GEDCOM with incorrect information. Once uploaded, the incorrect information will likely take on its own life and spread across the universe of online trees.
Also, uploading a GEDCOM comes with the responsibility of cleaning up the surplus data, so many people prefer to upload small GEDCOMs that are easier to manage and clean up or just manually enter data to ensure that only accurate and well-sourced information is added to WikiTree.