The reason back story is so awful is because it’s not back story. It’s back data dump. Actual back story, meaning some bit of prose that tells an actual story about a character or a world to fill in the missing history before the story proper starts, can be used to give depth to your writing.
Stephen King is famous for creating detailed back stories for his characters that make them seem all the more real to us. But if you want to see it done exceptionally well, read Ready Player One. Ernest Cline uses the first part of that book to set up the world and the main character’s entire life but it reads like a story so you don’t notice you’re being told about the Zactor Migration until you’re already deep into the story.
Seriously. Read it.