[LongMan]

MediaImporter does not use any of Kodi's scrapers. The metadata is pulled from the server. In other words, the MediaImporter is a "scraper" for your server.  Kodi's scrapers are only used for local files. You only need to set a scraper if you are adding a source (for files) to Kodi.

Hope that helps.

Cheers,
LongMan

Edit: To be clear you can use MediaImporter along side local files. MediaImporter will pull the metadata for its media items from the respective server while one of Kodi's scrapers will pull metadata for media files from one of the metadata sites.