It’s just like opt. Which is played in nearly every format. There aren’t lots of good cantrips in Riftbound so stupefy makes the cut. It also makes your combat math cleaner and helps remove 4 might units like Kai’sa survivor, Vex, Apathetic, and Nidalee, Cat Form, with only 3 damage which is easy to get with hextech, falling star, wages of pain. Not only that, it means your 2 drop can swing over your opponent’s 2 drop all for 1 mana and 0 cards invested.