they are not Standard-legal
Its like theyre conducting little experiments to see what we, the collectors, really want
Upon entering the battlefield, Omnath deals an amount of damage to any target equal to the number of Elementals its owner controls
Also, I can just give cards like Deafening Silence around the table to opponents who dont have a sacrifice package to draw cards later
Valley Floodcaller allows you to give Flash to all noncreature spells, allowing you a bit more freedom with when you play Enchantment, Sorcery, and other cards
The most used modes chosen in Commander are likely to be drawing two cards and dealing five damage to target creature, though the artifact destruction is also a nifty option if one of your opponents has a particularly annoying trinket on the board