You can only spread infection counters by attacking, so your opponents have a full turn to remove it before it becomes a problem, and you have to worry about it dying in combat, and the infection counter does nothing if the Patriarch is removed before you kill the infected creatures
Paying 2 mana to deny your opponent 1 is the kind of exchange thats only useful when youre far enough ahead on board to leverage the inconvenience of playing off-curve
Flickering it is especially amazing
Brainstorm One mana, draw three cards, then put two back on top sounds simple, but Brainstorm gets ridiculous once you pair it with shuffle effects
Many of the lands you want to target with Grazer enter the battlefield tapped anyways, so this offsets what would normally be an additional cost
You have to build it correctly, but that can get you an unblockable giant creature or maybe a One with the Multiverse