If that spell is countered this way, exile it instead of putting it into its owners graveyard, then you may cast it without paying its mana cost
Sending someones hard-earned graveyard back to their library can be a back-breaking play against reanimator decks, Underworld Breach, or even Thassas Oracle, as your opponent will often have too many cards in their library to win the game after putting their graveyard back into their library
Solving this case takes work, but the solved ability offers absurd card advantage, especially since lifegain decks tend to focus heavily on permanents
It seems weird now, because we have gotten a variety of decks that fit that archetype
Different binders have different uses, and different players use different types in different ways