It was not always thus.

In 1956, Elvis Presley was not the only superstar to make his debut on “The Ed Sullivan Show” — Callas did as well, with a lengthy excerpt from Puccini’s “Tosca.” NBC used to commission and televise new operas, including Gian Carlo Menotti’s “Amahl and the Night Visitors.” The soprano Beverly Sills was not just a guest on “The Tonight Show Starring Johnny Carson” but also a guest host. The mezzo-soprano Marilyn Horne appeared on the “The Odd Couple.”

David Gockley, the veteran American impresario, said that those television appearances drove a wider interest in the art form — and sold tickets. “Our audience knew a lot of these names because they were on television,” he recalled. “We don’t see the mainstream media paying much attention to opera these days, and it makes a difference.”

Peter Gelb, the Met’s general manager, said that dwindling television opportunities had forced the company to reach audiences in new ways — both by starting its Live in HD cinema simulcasts and through social media. Last season, he said, the Met’s videos were viewed about 7.5 million times on Facebook and YouTube. “We have to create our own communications systems,” he said in a telephone interview.

There are exceptions. “Sesame Street” still features classical musicians from time to time; the quiz show “Jeopardy!” has had dancers and musicians present clues; and Stephen Colbert has invited ballet dancers and classical artists on both “The Colbert Report” and “The Late Show.” But those kinds of appearances are fewer and farther between.