Quote:...“They flooded the market,” said Simon Cowell, perhaps the individual most responsible for turning amateur singers into superstars, with his roles on “American Idol,” “The X Factor” and “America’s Got Talent.” “There have just been a ton of shows, and something has simply gone awry.”

...The show with the starkest reversal of fortune is “American Idol,” a show once so overpowering that rival networks gave up trying to compete with it. Now “Idol,” which spawned the careers of Kelly Clarkson and Jennifer Hudson, collects ratings that are even worse than many of the woeful shows it once left in its wake.

Last week, the onetime blockbuster slid to a new all-time low for one of its performance shows, with only about seven million viewers (one season it averaged more than 30 million) and a puny 1.7 rating in the category its network, Fox, sells to advertisers — viewers between the ages of 18 and 49.

“Idol” once averaged a 12.6 in that group; as recently as 2011 it averaged an 8.6.

...The fall of “Idol” has been several years in the making: it slumped 30 percent each of the previous two years. But it fell from such a lofty perch that the show remained a hit. But its recent demise has sent the show into uncharted, inhospitable territory. Its precipitous drop means that the show is no longer the gold mine that it once was for Fox. One executive familiar with Fox’s ad sales said that “American Idol” generated close to $3 billion in profit for the network over its 13-year history. But little of that has been banked lately.

“They almost certainly had to offer make-goods this season,” Mr. Adgate said. (“Make-goods” are free commercials to compensate for shortfalls in ratings guarantees.)

...Even the last remaining music titan, NBC’s “The Voice,” though still one of the more formidable shows on network television, dropped to a new ratings low last week. That raised questions — among some NBC competitors at least — about whether the show’s downward spiral might be accelerated because NBC runs two cycles of the competition each season. (The median age of “Voice” viewers has also climbed from 42 in its first season to 52 this year.)

...The slackening in ratings for these shows is being matched by tepid record sales. “The awful stat is in stars created by these shows,” Mr. Cowell said. “The last true breakout artist we had was Carrie Underwood on ‘Idol.’ That was eight years ago.”

...One production executive who has worked on music shows and has had years of interactions with music executives, said, “I think the record companies are off the notion that they can create stars off these shows.”