The above linked article tells about Martha Wash. She did a lot of singing in her day, but didn’t get credit for it. She went to court and helped change the laws that make publishers give credit where credit is due.
She did a lot of voice work that we recognize, but we don’t recognize it as her. Next time you listen, think about how those voices got onto the albums. If it’s a male singer and there’s a part with a female singer, is she credited?