Dragon Ball Super's Illustrator has opened up about why Goku needs to be humbled. Dragon Ball's central protagonist started out as a young (alien) boy fighting against some overwhelming odds, but over the course of Dragon Ball, Dragon Ball Z, and (especially) Dragon Ball Super Goku has become so ridiculously overpowered that the Saiyan warrior outclasses any threat that comes his way - and now even rivals the power of the gods and angels! The criticisms about Dragon Ball's power leveling have been building for years - and this is what Dragon Ball Super manga illustrator Toyotaro thinks is being done about it:
"That's why, in the first half of [Dragon Ball Super Volume 16] we showed that there's a level of perfection beyond perfect," Toyotaro says in response to Dragon Ball editor Uchida's statement that Goku was essentially "perfect" at the end of the previous Moro Arc, when the Saiyan hero finally achieved fully Mastered Ultra Instinct. As Toyotaro further explains, Goku shouldn't be too cocky yet about the power he's achieved - namely because he knows plenty of people he hasn't yet surpassed!
"There's plenty more for Goku," Toyotaro teases. "There's Whis, Beerus, also the Grand Priest."
It's not just that there are these cosmic figures out there that Goku hasn't yet surpassed - there are other warriors that are redefining what power levels mean in Dragon Ball. Toyotaro and Uchida tease the current developments happening with Vegeta and his God of Destruction powers finally emerging while discussing how "seriously cool" this new Vegeta is going to be, and how fun it is that Vegeta and Goku are now on equal (but different) levels of power. They wouldn't reveal which Saiyan hero will ultimately be revealed as being the current strongest, which could be saying everything without saying anything at all.
At our current point in the Granolah Arc, Goku has been taken down by Granolah's deadly vital point strikes, after being duped by a clone body Granolah used to measure the Saiyans' skills. Only Vegeta is currently left on the battlefield, and his battle with Granoloah has only confirmed that the Cerealian's wish to be the strongest warrior in the universe has indeed been granted. However, Vegeta didn't fall like Goku when hit with a vital strike; instead, the Saiyan Prince's life-or-death moment in battle forced him to evolve into a God of Destruction form.
The power that Granolah and Vegeta go at it with during their next round of battle will indeed be a humbling reminder to Goku that he still has ways to grow - if he's even awake to see the battle unfold.