A singer of limited talent can be promoted and hyped based on personality, "attitude", sexiness, and general hipness. (This is taken to the ultimate in rap, where personality and "attitude" are everything.)

An instrumental piece, in contrast, rises or falls on the quality of the music and the skill of the musicians, and the best musicians are not likely to be the most marketable personalities. (Think of the architypal sissy boy on Our Gang or Little Rascals who had to stay inside practicing his violin while his friends were free to roam the neighborhood making mischief.) With instrumental music, promoters simply have less power to engineer a phenomenon.

I mean, you can bolster a mediocre singer with anonymous expert-but-nerdy studio musicians playing from behind the stage. But what can you do with a sexy-but-amateurish instrumentalist?

Look at any rock concert from the 1980s on up, and you'll see that the TV show "American Idol" is aptly named. The music business is no longer about creating and selling music. It's about creating and selling idols.

"I mean, you can bolster a mediocre singer with anonymous expert-but-nerdy studio musicians playing from behind the stage."

You can do more than that...you can correct out-of-key singing with technology that makes everything sound in tune; you can create the illusion that the voice is doubled (an effect called "chorus") so that the singer sounds more powerful; you can do all those cheesy manipulations that Cher uses on "Believe" to make her voice sound robotic (didn't we get enough of that in the 1970s with Peter Frampton?)...basically, we are in the age where all pop stars are just a hair above Milli Vanilli in the authenticity-of-singing department.

While double-tracking vocals to "punch things up" goes back to the Beatles and even earlier, all these electronic modifications (and the public's acceptance of such heavily processed vocals) has really lowered the bar for the top-40 stuff, though real singing is still happening in the margins.

you can do all those cheesy manipulations that Cher uses on "Believe" to make her voice sound robotic (didn't we get enough of that in the 1970s with Peter Frampton?)...

The difference here being that Cher's cheesy manipulations relied on a piece of computerized equipment, while Peter Frampton's relied on his own skill as a vocalist and guitar player. The device he used was a tube that relayed the output of his guitar speaker to his mouth, where by forming the word, it sounded like his guitar was "Singing" similar to the device used by people who have had their voiceboxes removed.

Yeah, the vocoder, I'm aware of how it works. I was a guitar geek as a teenager.

I'd actually argue Cher made a bigger contribution to music from 1965-1975 than Peter Frampton, whether or not she could rip off a guitar solo. Well, Cher plus Sonny and all the people behind the scenes who wrote the songs and arrangements

Frampton might have been unlucky to get what he most wished for...a huge hit as a solo artist. Perhaps if he had been in a long term artistic partnership like Jagger/Richards, he would have produced more worthwhile music.

Your a little off. It's not call a vocoder. It's actualy a talk box. As the previous poster said, the talk box disengages the sound going to the amp's speaker, and rerouts it to a tube. The tube is placed in the mouth, and the sound of the guitar is used to create a "talking" effect. The thing is that Frampton had to have some talent to do that, where Cher did not. Adding computer effects to your voice does not make you a good singer. As far a musical contributions go, I think I would agree that Cher has made a significant contribution, probaly more so than Frampton.