Say you have two forms on one panel (don't know if this is the best example or not, but here goes).  You want to move a field from one panel to another.  You'd have to do that in code with the traditional approach.  With the "queued" approach, you'd just queue all your components to the parent container and it would auto-add them to the correct subcomponent as it finds them in the markup.

With this, the order does matter, though.  Suppose you had two components you wanted to queue with the same id, completely different components.  If you reverse their order, then they're auto-added in a different order.