Because the image list for project creation in Scalabel Format can also contain labels within each frame. For example, you can upload an image list like examples/image_list_with_auto_labels.json. The labels in this email list are generated by an object detector. The labels will be automatically loaded in the tasks and shown to the annotator for adjustment.
Another use of this function is to provide further annotatoin adjustment for existing labels generated by Scalabel. You can directly upload the exported results from a previous annotation project and the labels will show up again in the new tasks.