In music it has been the standard for hundreds of years that the composer of the music is not the one performing it.
And actors don't write or direct or shoot movies either.
Totally different. When someone performs a piece by Beethoven everyone knows they are performing his work. Very few Beyonce/Taylor Swift/Nsync/whatever fans could name the people who actually write the songs. Classical composers were total rock stars of their period, they were well known and the face of their music.
Modern pop musicians have almost all of their work written by people who are intentionally kept in the shadows.
Being a composer is not a public facing profession anymore.
People mostly don't care about the composers/producers of modern pop music. But if you want to find out it is really easy on all music platforms (Spotify, Youtube music etc).
Being a performer and a composer is a very different skill set and a very different business model.
Also, it is very difficult to compare the amount of fame of someone in 1800 vs someone in 2020. I am not so sure being a composer was ever a "public facing profession".
I stayed for the credits of a movie the other day and they listed all the musicians at the end. ~80% song attributions were formatted like: `Song written by "unknown person". Performed by "Famous musical act"`. Maybe Warhol was like a proto version of being famous despite special talent, but it is almost all we get nowadays. I wonder if huge companies like Disney know that by distributing power (some people write, others perform, others do marketing, etc.) they can ensure they have final power and any artist can be replaced easily.