For example, you have database and make regular backups but don't make regular control restore (sure, it is bad)
In database there is small bug in unused stored procedure: this procedure uses paramer1 in second procedure, which was dropped.
And after damage of real database you try to restore backup and get the dependency error, you get unrestorable backup (I don't know simple way to fix it).
Will be useful to make restore with some paramater (like IGNORE_ERRORS) which, for example, automatically comment the body of procedure with dependency errors.
And in addition, there is gbak paramater "no_validity". Will be useful to have ability to ignore only wrong conditions, not all.
After restore you can simple fix one problem in one place, but with "no_validity" you get inefficient database.