This focuses on excellence within a task or role versus excellence that is external to a given task or role.
(1) Excellence that is external to a given or specific function does depend on being and/or doing the extraordinary. Think of Olympic competitors: they set the standard for physical excellence and they do it by being and doing the extraordinary. Think also of past masters Da Vinci, Beethoven, Frank Lloyd Wright, Caruso, the Wright brothers (the Marx brothers ...). Each and every one was extraordinary and did the extraordinary.
(2) Excellence that is within a given or specific function is most often dependent upon ordinary people doing ordinary things with extraordinary care or attention or love or precision. Think of the product engineers and workers at a seat-belt factory. These are ordinary people who do ordinary things in extraordinary ways so that you and I and babies stay safe.
The quote is actually presenting a logical fallacy by comparing two unlike, disparate things to each other and concluding that the one cancels the other out and negates the other. In truth, the Beethovens will never be--can never be--cancelled out by the seat-belt designers and workers though both will continue to exist and to be true.