I know The Creators respond if there is a nasty thread goin' down, but I too have the same frustration in submitting artists that don't get listed, or even acknowledging that I've submitted one.
Over on ActiveBass, I've submitted Ron Carter (jazz upright) as an artist that surely should be included (Justin Timberlake is listed fergawdsake), and ActiveMusician even lists books of Ron Carter transcrption . . . but he is not listed as an artist DESPITE my multiple attempts to get him there AND having put up a post about it.
I do get the feeling, recent post by Sean Kelly notwithstanding, that since this site (and AB)seems to be well-visited as it is, not much more effort is being put into its upkeep.