Why do singers from the 70s & 80s rarely make music now?

There was a group in the 70s called The Sylvers. Supposedly, they were to be the next Jackson's or almost as talented. In the 80s there were lots of R&B groups and solo singers, like Sybil, CeCe ton, Gwen Guthrie, Shirley Murdock, some of whom had big hits. Though some singers p away or retire, why is it that other current well known singers hardly ever make any new music these days? Do people become less talented the older they get in the music business? Gladys Knight, Anita Baker, and Chaka Kahn are still big name, great singers but they don't make songs as often as they did years ago. Even Prince (aka His Royal Badness) is rarely heard from these days. And this is a guy who sings lead vocals and all the background vocals, and plays every instrument on his songs. Other than Bobby McFerrin or Michael Winslow (if he were a musician not a comedian), who else can do all that?