Why you don't want your backup solution “In-App” in a tab in Salesforce?

One of the important use cases for backup, is in case you decide to leave Salesforce, or in case Salesforce goes down. You don't want to be dependent on them to access your backups.
If you're managing backups for multiple orgs, you have to log in/log out multiple times. With our application, you manage all of your backups in a single place.
Eventually, you're going to reach your limit on custom tabs and you don't want to waste tabs on apps that you might not use very often.
It's easier to control user access to an external web app.