These combine to add hundreds of new cards to the available pool
This I think is the best example of why, the card is pretty balanced (somewhat underpowered but still perfectly playable) and I think it is really interesting too
Wizards has a history of waiting too long or trying something else first (see Hogaak and Bridge from Below) and unfortunately, what they did is condemn us to at least a couple of months where Oko, Thief of Crowns is definitely the best thing to be doing in Standard
Green decks have so many ways to make land drops and maximize these creatures, especially since their respective counter doubling abilities effectively remove any ceiling one might place on them
Obviously, X-spells were great mana sinks, but artifacts with healthy activation costs were also big-time favorites, and Mishras Factory was a potent buy-out for those spots where you needed to Mana Drain but had nothing to use it on, plus nothing on top of your deck