The motivation behind working with publication editors in the Boost Nomination Pilot is to add a secondary layer of support for writers. Publication editors often work closely to help their writers clean up their stories to improve quality and increase the story's likelihood of getting Boosted.
(As a writer myself, I know how much my work is improved by having another person review it and provide feedback!)
That said, half the stories that get Boosted on Medium do not go through the Boost Nomination Pilot -- they are Boosted directly by our internal curation team. To learn more about that process, I recommend this story written by the head of our curation team: https://blog.medium.com/updated-guidelines-for-boost-47799aad8899
Let me know if you've got more questions!