Directly referencing children within a hierarchy gets cumbersome at scale, and Godot's signals work best within the local instance. When you start moving things around in the tree programmatically, or dynamically instantiating objects, it is handy to be able to emit a signal globally and have potential receivers "listen" to that signal wherever they may exist in the tree. This video goes over creating a centralized signal / event management system and using it for a few different scenarios.
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