A single attack destroys everything, including lands, but Anara ensures that your commanders survive
Of all the one mana targetted discard Blackmail certainly scales the best into the game
Additional risk is also assumed when tutoring for cards that arent going to a place where you cant immediately play them or protect them for later use, such as the graveyard, and this is especially true if you have to reveal the card(s) you searched for
First of all, it counters a spell, meaning that whatever card your opponent was trying to play goes straight to the graveyard and has no effect on the game
Other examples are Orcs, Dwarves, and Thrulls
It has targeted other cards via errata in the past but has never opted for an outright ban