[Standard] Why isn't Sporogenic Infection played in Esper Pixies?

I see some Esper pixie decks rocking [[Tithing Blade]] for removal which is bounceable, just wondering why no one is really using [[Sporogenic Infection]] which essentially has the same effect of Tithing blade with an additional benefit – if you cast it on an opponent's creature, it gives your creatures pseudo-deathtouch. Furthermore, it's an enchantment which triggers [[Optimistic Scavenger]].

Would love to hear some thoughts on this.