Epic Meepo
Hero
It doesn't say that at all. I'm looking at it right now.There's text on page 36 explicitly allowing for custom backgrounds with the DM's permission.
The 2024 PHB says, "You can choose any of the backgrounds detailed in chapter 4, and your DM might offer additional backgrounds as options." On page 177, it adds, in reference to a background's non-rules text, "Alter the details of this narrative however you like." That's it.
For comparison, the player-facing "Customizing A Background" section in 2014 PHB says, "you can replace one feature with any other one, choose any two skills, and choose a total of two tool proficiencies or languages from the sample backgrounds."