Not sure I have quite understood.
Here’s a scenario as an example. You have set up a large number of scenes with individual tags turned on and off as appropriate. Now you want to add something and create a tag for it such that will only be visible in one scene. Without extension, the new tag would be switched on in every scene by default. My understanding is that the extension avoids that when switched on and so avoids the need to laboriously go through scene by scene switching it off.
I guess the way it might work if it were built in is that when you click to create a new tag, you might be asked if it is to be unique to the current scene (would that work?). Say no, and everything would be as default now.