This is because, frankly, we've gotten so many board wipes over the last few years
Savior of Ollenbock has two separate abilities, which means you can permanently exile something by sacrificing or otherwise getting it to leave play before the first ability resolves
The former has a power and toughness equal to the number of Soldiers you control
The reality tends to be more uneven, with lower-quality spells hopefully doing enough to maintain momentum as you dig for highly broken outliers like Jeskas Will, Peer into the Abyss, and Ad Nauseam
Typically, green decks have a lot of lands anyway, so youll likely create a Clue token almost every turn
Examples are Battle of Wits (which requires a huge library to win the game) and Scapeshift (which requires playing enough Mountains to one-shot your opponent with Valakut triggers)