In the society of 2025, the method by which everyone has been made "equal" is analogous to the methods of ensuring that "No Child is Left Behind."
With No Child Left Behind, in order to to make sure that no one can become intellectually lost in the learning process, the instructor must make the brightest wait while those who can understand only after lengthy demonstration, practice, etc. finally grasp the concepts being taught (if they ever do). Having the bright students wait is equivalent to imposing the handicaps upon them as in Vonnegut's short story. So, the bright students are those like the beautiful ballerina, Harrison, and his father; those slower ones are like Mrs. Bergeron, Harrison's mother.
In both cases, the weak (meaning those who lack talents) cannot be strengthened without weakening the strong. For, without competition, the stronger will not achieve as much. After having his thoughts drowned out with noises and shocks, Mr. Bergeron begins to not remember what higher thoughts he has had since he does not have any occasion to exercise them. Likewise, in order to teach everyone, teaching to the "middle" must be done. Only mediocrity can survive in the society of 2025 ( e.g. "...the ballerina must "apologize at once for her voice" as she reads a bulletin) and in No Child Left Behind.