A little disappointed that the writer never attempts to address the title of the post, which is either a) why most people can't juggle a single ball, or b) how the author even knows this to be true, aside from some limited anecdata.
My (admittedly limited) juggling experience would indicate something closer to "Anyone can juggle", or that your average person, particularly young people, can learn to juggle one, two, or even three balls with an afternoon of practice, but I suppose that makes for a worse title.
Long, long, (long) ago I used to teach people to juggle at the local Renaissance Fair. I would say I could get almost everyone to flash 3 in less than 30 minutes. Most people walked away having at least 5-6 successful throws. The only people who really couldn't learn are those who don't like to fail and won't even try. Learning to juggle is repeated failure and you have to be willing to persist. Learning 5 clubs (very briefly) took me many years of repeated failure.
> "Anyone can juggle"
Technically this is not incompatible with the title. Just uses “can” in a different sense. The title would be using “can” in the “has the skill already”, while you use “can” in the “able to acquire the skill” sense.
It is not hard to imagine that most people when asked the question “can you juggle?” would answer in the negative. That’s what the article’s title describes. And then if those people, given sufficient motivation can learn to juggle that leads to your sentence. And they both can be true at the same time.
I agree that it would be nice to provide source for the claim though.
I would say no to currently being able to juggle, but that's because I don't consider one ball to count as juggling.
If you specifically asked if I could juggle one ball, I'd say sure. And I just checked, one ball goes fine. And I've never practiced juggling. I'm pretty skeptical about that ability being the minority.
So I also want more explanation of the title.
I am not fully certain but juggling is moving objects in a predictable path so as to repeat without dropping.
In my understanding of the OP, juggling 'one' is being able to throw an object consistently to another hand without handing it. This is an intentional throw of the ball from one hand to another without "moving" the other hand to compensate.
Throwing from one hand to another, either directly or in an arc, requires the motorskills to move an object consistently while understanding the speed, trajectory, and then moving the other hand to receive (not catch) it as expected.
There are multiple elements at play with 3 object juggling. One must throw an arc toss to the other hand, while holding an object, then throwing the object in said hand to free the hand to catch. In reality you are holding two objects with one in motion - until you get the double arc which is now technically juggling.
Three bodies in motion, two hands that are each making circular or figure eight motions, while maintaining a consistent arc and speed (XY (no Z) + T = arc) where the mind either tracks or forgets allowing the predictable movements work themselves into only tracking one object at a time - by setting it's path and then shifting focus or attention to the next.