Just like many of us, the big names of 100 years ago often photographed mostly whoever they associated with. A painting was more dignified than an art-photo.
Most of Stieglitz photos are of Okeefe who probably wasn't famous when he took them.
Most of Edward Weston's portraits are of the women he was banging
Clarence White's generally photographed family and friends, creating most of his good work before he got into teaching famous people.
Kasabier, with the exception of her Indians, mostly photographed unfamous people.
Day was famous for his selfies on the cross, but mostly photographed unfamous people
illumiquest has photographed me, and I have been on local access TV, in the newspaper, and generally see 4-5 people I know whenever I go to the grocery store or walmart. If I were a musician rather than an amateur photographer, I'd be famous, but I have determined I have no talent in singing, piano, or drums.