@crimsonaudio probably has more on this, but surprisingly few artists write their own music. It’s an especially low percentage in pop, where one man none of us has ever heard of has written more hit songs than Michael Jackson and Madonna combined, and entire albums are written formulaicly by teams in Los Angeles over just a few days.
This article talks about how that’s led to a sharp drop in the timbral diversity and harmonic complexity of popular music (i.e,. why so many of songs sound alike) as measured by algorithms.
So if you think the music of your 80s or 90s youth was better than today’s, you’re actually mathematically correct…