If you start too late in the action where all the interesting bits have already happened off stage and your main character just as to deal with the consequences of post fecal matter meets ventilation system, you’re stuck with the problem that while your character is struggling with all the problems he has to face at the start of the book, the action has to be paused so you can catch your reader up with all the backstory as to why what is happening right now on the page is important. Backstory is hard to write in an engaging fashion. I’m not saying it’s impossible, but since the main character has already survived it or, in some case, wasn’t even born while it was happening, it’s not engaging the reader with any sense of immediacy.
Then you have the stories that start (usually in the prologue) with the main character (or worse, the main character’s mother/grandmother/great-grandmother etc) being born. The bad person shows up, does menacing things, and then disappears. The character grows up (or worse, his entire ancestral family grows up) and then fights the big bad as though the baddie hasn’t been preparing and waiting for years. Whether the kid is old before his time, preparing for his fate, or he’s completely oblivious until the letter from Hogwarts arrive, it doesn’t matter. We’ve been told this story so many times there’s a brilliant evil overlord list that should be used as a checklist by your big bad. That story can still be told, but it hast to be masterful. The Thief, by Megan Whalen Turner is a masterful boy who is the chosen one. The whole series waltzes with the old, tired fantasy cliches and leaves them breathless and blushing in their stays on the side of the dance floor.
It can be done. It’s just freaking hard to do.