Basic Plot: a dystopian future wherein all the productive, intelligent people are committed to a "mental institution" where they more or less keep the world running.
I read it in the early 1970's, in a science fiction anthology that I can't seem to locate in my collection. It may very well be “The Marching Morons”, but I don't think it is.
This has a couple of similarities to an Asimov story called Profession.
Most people are taught their professional skills via some sort of mind tape, except for those few who are unteachable and are therefore kept in a House for the Feeble-Minded. Of course, it turns out that these are the only ones who are intelligent enough to create new tapes.
IT sounds like the Marching Morons to me, but I, too have not read it for years.. But it has Earth as "a civilization of morons protected by a small minority of hidden geniuses."
However.. a quick google search found an online version-- here. With luck it's your story.. If not, it's still a worthwhile read :)
Harrison Bergeron maybe? Short story by Kurt Vonnegut Jr. The population is "equalized" by physical instruments to handicap them closer to "normal" i.e. limits hearing, vision, and mobility to bring their abilities closer to the bell-curve definition of normal.
The title character rebels and declares himself emperor.
