No song composed by a just one person has reached the top of the Billboard chart in almost 3 years. https://www.billboard.com/articles/business/chart-beat/9473248/hit-songs-written-by-one-songwriter-fleetwood-mac-dreams-stevie-nicks/">https://www.billboard.com/articles/...
The reasons are historical, not artistic. Songwriters joined together to form ASCAP & helped create a legal system that rewards composers. But musicians, sound engineers, producers, etc. never did this. So they now need to share in songwriter credits to get performance royalties.