The problem with this was that players could, for example, trigger a Werewolf by playing no spells that turn and then, when the trigger was on the stack, play instants
Crystalline Sliver outright nullifies all targeted removal along with a number of other solutions
It must be something that it could legally enchant, but not necessarily something it could target if it were on the stack
Its an incredibly elegant and carefully designed solution to the onboarding problem that a lot of TCGs have, and I wouldnt be surprised if other card games look to this for their own equivalent in future
Its ceiling is so much more
Oh, also, if it goes into your graveyard from anywhere it instantly gets shuffled back into your deck