The reason why it is low on this list is that this deck is in trouble if opponent have good counter to spell castings and has no good counter for non-dragon/machine focused decks
I think if the ability returns in upcoming sets, it could really show how good it can be
All of this is to say that Oko is extremely hard to answer in combat, so it largely requires a spell to deal with it (or, as we see in Throne of Eldraine Standard, you can go way over the top of its threat generation by, for example, making lots of 2/2s with Field of the Dead)
Dataminers have revealed that players will soon be able to obtain rare cards in a guaranteed way
Myr Retriever Rarity: Common TYPE: Artifact Creature SUBTYPE: Myr CMC: 2 Mana cost: USD: $2.89 EUR: 1.07 TIX: 0.03 EDHREC RANK: 877 (1/1) When this creature dies, return another target artifact card from your graveyard to your hand
Polymerization 27847700 729