I think you’re missing the point here. Not everyone that uses the bot uses it for their own stream. Sure, maybe about 10% use it only for their own streams, but the remaining 90% use it for other people’s streams. Do you think Ninja or Soda need a bot like mine to notify ppl when they are live? Nope, but I have at least a dozen servers tracking when either of those 2 go live so they get the notifications in the format they choose in their Discord servers. So any sort of onboarding prerequisite will GREATLY limit the broadcasters that can be tracked and announced because it would be an all or none process.
Imagine getting a bot that does what mine does and when trying to add a channel to get announcements for a particular channel, it would respond with "Sorry, but that channel hasn’t finished the onboarding process so I can’t announce them here. 
". Nobody would want to use that product.