Isn't the point of DontDestroyOnLoad to carry an object over to the next scene? If that us the case, why do you need new instances of the object in all scenes? Won't it just carry the object over from the one scene over to all other scenes?
Viewing post in Why DontDestroyOnLoad is Bad comments
It makes playtesting easier and lets you separate out the player from the transitions, which is valuable once you have a complex class.
When I'm testing a level, I drop the Player prefab there, and that's fine. But if I compile the game with it there, and I load into that level from somewhere else in the game, there will suddenly be two Player objects. So I'd either have to make a bunch of logic for figuring out which Player is the duplicate one and deleting it before any of the Awake() hooks get called to register inventory and UI and whatnot, or go through every level (aside from the first one) and disable the Player object in it.
I also can't put it in the main menu, because if I stop mid-level and go back to the main menu, there will be two Players there, so I'd need a scene with only the Player object that will immediately load the main menu and take the Player with it.
There are other advantages, but that was the big one.