Nobody bats an eye when Dante From The Devil May Cry Series gets into a scuffle with The Despair Embodied, because fighting grody monstrosities is Dante's whole "thing". Kirby, on the other hand, is a cutesy game mascot from a franchise targeted at eight-year-olds which, in most final boss battles, jumps unexpectedly from cute ball-shaped guys and little adorable monsters to "Rise! Oh, Dark Lord of Despair! / Crush the stars! Lay waste to care! / Rise and cover the land in sorrows! / May your symphony of emptiness bring the end of all tomorrows!" (an actual verbatim quote from a Kirby game).
The important thing, though, the thing that makes "Kirby final bosses are gods and eldritch monstrosities" work as an enduring meme and phenomenon which really sticks with people, is the fact that the games -- and the developers and advertisers ouside of the game -- steadfastly refuse to acknowledge the incongruity. Like, Dark Matter or the Ultimate Life Form or whatever are just another boss for you to fight. The Destroyer of Worlds is treated as special and unusual because it's the final boss, not because it's the Destroyer of Worlds.
I'm just saying, it would lose something if it was like ... self-aware about it, on any level.
