"There are instances where it could come handy to have dynamic control of the layers in a group or a pinboard.
For example, you could press a button and you could bring to front an item in a pile, or push it back by a few layers, depending on a specific parameter."
no they are saying that they want to change layers in play mode (not edit mode) via triggers and actions.
So items in the back could be brought to front in play mode for example.
Show & hide don’t really affect the order of the layers. The only way to change them is in authoring mode, but there are scenarios where you might want to do it dynamically inside the app.