Actually, I didn't use juggling as an analogy for that. I compared it to the unbendable arm practice. I don't really have a direct application for juggling, either. Both, from a training perspective, are to train body abilities.You mention juggling. You used juggling as an analogy to highlight the differences between application and demonstrations. I fleshed out your analogy, so that it addresses the difference between what one can do and what one can pretend to do. As I said, I can juggle three balls pretty well... I don't drop them and can even do a few tricks. But I can't juggle more than three items, and I certainly can't juggle chainsaws. How do I know this? Because I actually do it.
I presume when you juggle, you actually have some objects (guessing three balls or beanbags, but could be anything) and you literally throw them around in a continuous manner. That's application. You are, at that point, juggling. You may be good at it. You may not be good at it. You may be REALLY good at. How do you know how good you are at it? Well, when you try to juggle, you get a lot of immediate feedback.
And the point is, some folks can't do what they purport to do in a demo, and some can. I can juggle three balls. From a demonstration, it's impossible for a lay person to distinguish between someone showing them functional expertise in its best light and someone showing them complete theater... a façade of functional expertise that is unrealistic.
I hope this explains it a little more clearly.
You're trying to use that to yank things over to a tired, worn-out attempt to argue something you've actually said twice you'd drop. But you can't. If I'm really lucky, you'll go back to the flying analogy, wherein you can only see your own view of the topic and nobody else's.
So, to bring it back to what I was talking about, I can do an unbendable arm technique. And I sometimes make that claim, so we're all good.