Even commodities with clear levels of use-value demand like gasoline, eggs, or palladium fluctuate in price for similar reasons, a combination of demand, investment speculation, and, if not always nostalgia, at least some form of emotional connection to a product that seems stronger than its value in use or consumption
Lastly, Stadium Trainer cards are played in the middle of the arena and affect both you and your opponent
As for the green-black Partners , theres Reyhan, Last of the Abzan, who saves counters, and Ikra Shidiqi, the Usurper, who synchronizes with the big beaters by giving them toughness lifelink
My first Commander deck, and the one I still play in Bracket 4 games, is Savra, Queen of the Golgari, but I've built numerous Golgari Commander decks in the two decades since