Backup archives are easily portable. If any emergency requires that you switch servers it’s easy to quickly restore a backup at a different location. You don’t want to be desperately searching for files in a time of crisis.
WordPress makes this exceptionally easy. You only have two parts to any WordPress backup: the core files and the database. If you have those pieces you can instantly restore your site.
But there are important data outside of your site that also need to be recovered. Most hosting plans (including the ones offered by InMotion Hosting) provide email services as well. This is why a backup service for your entire hosting plan is so imporant. It will grab everything and store in a safe location.