It has been in the news in the twin cities (MN) area lately. It seems when ever there is a new fad, positive or negative , school admin's are always quick to stomp it out claiming it's a distraction to the learning process.
Many kids learn in a non conventional fashion. My oldest is on the autism scale with Aspergers syndrome and one of his traits is he is able to out think a calculator on math problems, and was able to out think his math teacher too, but he couldn't put his process on paper to show his work so he always got stuck with low grades. Something like a fidget spinner would have served him well back then. (he's 29 now).
Some kids are appropriately getting special I.E.P provisions to allow them to have fidget spinners to help them concentrate in class. This is something that crossed my mind when the spinner concept first showed up here on the forum.