To the extent that autofiction is a movement it seems to be one created by critics, which perhaps explains why this genre’s generally acknowledged membership is so homogenous.
I can't help but wonder if this issue might be fixed at least a bit if we had more critics of color? If we're thinking that white critics gravitate towards white writers, would critics of color gravitate to writers of color? Or would the also go for white writers because that is what their white colleagues do?