He saw the potential of the format as a vessel for social play and tirelessly advocated for it as a way to make and spend time with friends
Destroying a non-Demon creature is outstandingit can kill pretty much anything and is abusable with bounce and flicker effects
If trading individual cards, trade-in for cards that can go in multiple decks : This is similar to the reason for rare and mythic dual lands
If past releases like Ezuri, Stalker of Spheres haven't lifted Sage of Hours to the stratosphere, I suppose it makes sense the new set - while very popular - wouldn't either
If you deal five damage with a Saproling, you make five more tokens, making it an exceptionally strong card to build around
Gogos base ability is already on par with cards like Strionic Resonator, and its scalable, so you pay 2 mana for one copy, 4 mana for two copies, and so on