Even if your theory is correct, how could someone claim that this is a great idea and give directions on how to build such a piece.
Because it's fun?
For the same reason I made a cue lathe out of Legos and an 18v drill? (See http://www.youtube.com/watch?v=Mt0jBn1yMfI for the Lego lathe)
Ingenuity is the mother of invention. I've so far seen multiple versions of the ball polisher with people continually making improvements. I have a few ideas in my head to improve on it (have made two so far, 2nd one quieter and less vibrations then the first) as well. At some point enough of us will have shared our experiences with what makes it better and what didn't that we'll have a perfectly working, cheap, fairly quiet ball polisher (as long as we stick with an orbital polisher it will never be quiet).
There is a quote from Thomas Edison that I love:
I have not failed 700 times. I have not failed once. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.
The power of the internet will let us spread out those "failures" to many people to get to the solution much quicker.
Brian