The female singer-songwriter whose relative neglect staggers me is Laura Nyro.

As for Carly Simon the songwriter vs Carly Simon the singer, they seem pretty much co-extensive. She wrote or co-wrote almost all the tracks on her compilation albums (not counting the Christmas ones): 83/88 tracks, not songs, until I got tired of counting.

It looks like Mockingbird (Inez and Charlie Foxx) and Nobody does it Better (B Sager, M Hamlisch) are the big hits she did not write.