Why do I need to spread operator in the getter method?

so right now, I’m learning about provider state management from maximillian on udemy, and he keeps using spread operator as a getter. For example:

 List<Order> _orders = [];

  List<Order> get orders {
    return [..._orders];
  }

Why do we need to use the spread operator?

I can use this code and it runs fine.

List<Order> _orders = [];

  List<Order> get orders {
    return _orders;
  }