Sure, cards like Silence and, especially, Orim's Chant have made this card obsolete, but the fact that this is a cantrip makes it yet another attractive instant that can be tucked away underneath an Isochron Scepter for infinite uses
While you will need to be playing a healthy number of Deserts in order to get the Zombies, many of those Deserts are quite good
Takes One to Kill One: Number Wall creates this situation, by protecting Number monsters from destruction by battle, unless they battle other Number monsters
Not every aggressive deck will have Hazoret, but the theory will be the same for all of them: a very, very short game with some amount of reach to close out the game
When Sheoldred hits the battlefield, it forces each of your opponents to sacrifice a non-token creature or planeswalker, all but guaranteeing you get a good card off the board
the Speed and Power Advantage gained from this is enough to finish the game through the use of their other, less situationally effective attackers