For songwriting, I don't think that's true. Gershwin, Cole Porter, Johnny Mercer, or even Burt Bachrach are as well know or more so than the performers who sing their songs.
Big songwriters such as Paul McCartney or John Lennon or Elton John are also known for their singing career. Sure, there were/are Gershwin, Porter, but they seem to be exceptions. I mean, can you name 10 biggest songwriters in pop, rock or Jazz these days who are not the performers as well (such as James Blunt or Elton John)? Can you name who wrote "Over the Rainbow" (the answer is Harold Arlen and E. Y. Harburg), considering that's one of the most popular songs of all times? If you go online, more often than not you will find the lyrics and who sang the song, but not the writer who wrote it. I do think songwriters, and to an lesser extent screenwriters, are more "unsung" than say novelists and playwrights.
And it's ironic because I was just reading an article in Entertainment Weekly talking about the Idol alums and how some of them are not doing well, despite their Idol popularity and singing abilities. And the idea seems to be that the songs are more important than the singers in these cases, and the reason why they're not doing well is that they don't have good songs.
And yet, when is the last time you read about the songwriters in a mag like that? When's the last time you talk about screenwriters other than just a casual mention when talking about an upcoming movie -- except maybe screenwriters like Charlie Kaufman (for his wacky psychological comedies/dramas) or Michael Arndt (because of the success of Little Miss Sunshine).
I think the issue is that with performing art (music, movies, etc.) the performers are usually what people see and hear. It's also usually a collaborative effort. (famous) Playwrights seem to get a bigger "NAME" on the marquee because they, along with the directors or actors, do draw crowds. And plays are as much about the words than about the acting....
That brings me to a thought. Perhaps it's all about "who draws the crowd." Story matters most, but after that, who brings people to the venues? Is it Madonna or some songwriters who write her songs? Is it Stephen Spielberg the director or Charlie Kaufman the writer (in the both cases, they both draw crowds)? Winning an Oscar, for example, may push you to that level. In the case of, say, Cole Porter -- he drew the crowd. People, including singers, wanted to hear (and sing) his songs. It wasn't really about Frank Sinatra, but it's about Cole Porter's wonderful song sung by Frank Sinatra.
It does come back to the "story" (or songs) -- the reason while Cole Porter was famous was because he kept giving us wonderful songs that many different singers want to sing -- they weren't just work for hire. Same with Charlie Kaufman -- his unique movies (stories) make him a name -- a name many directors and producers and audiences seek.
So, I guess, for a writer to make himself a name in "show" business, he or she has to carve out a niche for himself, and somehow he or she has to be bigger than the stars or even the story itself. For example, outside of the screenwriting circle, I am not sure how many people know who David Koepp is, but he's written many, many blockbusters. Unfortunately for him, the movies he writes are usually much bigger than he is -- blockbusters are about the effects and the stars. But Charlie Kaufman or Alan Ball is always bigger than the movies they write...
The screenwriter's name is always in the opening credit, along with the stars and director. Songwriters' names are always listed on the album with the songs. So I don't think they're being ignored or uncredited for their work. However, the question is:
Do the audiences take notice?
