[costco]

It's because the singer and songwriter are no longer distinct. Pop used to mean a beautiful new rendition of an Irving Berlin or Cole Porter song. Or a hitherto underappreciated song like "Mack the Knife." Now everyone's writing their own songs and it's a disaster. Few realize this.

[tomjakubowski]

Solo singer-songwriters have been virtually nonexistent in pop charts for the past 15 years

https://www.rollingstone.com/music/music-features/hardly-any...

[costco]

The artists themselves are usually coauthors with other people they collaborate with. I'm not aware of a modern day figure with an analogous role to one someone like Irving Berlin had at the time. The songs that chart today are lyrically new and are not new covers of songs from 10-20 years ago. There is no more Great American Songbook in the sense of songs that are written once and covered many times.