Gibbs is an underground artist with a strong discography (apparently at least 1 classic) that's garnered universal respect, that sounds like a good deal of people on that list, someone of which group artists being ranked individually.
Ignore the numericals
- Prince Po (accomplished within Organized Konfusion, what?)
- Posdnous (accomplished within De La)
- Trugoy (accomplished within De La)
- Del (...George Was Here, 1 classic)
- Ras Kass (Soul on Ice, 1 classic)
- Lord Finesse (lead a movement, but which solo album resonated anymore than Gibbs)
- Big L (1 album in his lifetime, is Poor & Dangerous enough to outdo Gibbs' output?)
- OC (same as Finesse)
- MF Doom (literally the same career parameters as Gibbs)
- Kool Keith (lot of material but most accomplished within Ultramagnetic)
- Havoc (achieved within Mobb Deep)
- Cormega (similar career to Gibbs)
- AZ (Doe or Die, 1 classic)
- Grand Puba (Brand Nubian)
- D.O.C. (has a classic and his pen with Cube's powered NWA, but Gibbs has consistency over him)
- Large Professor (major contributor as a producer, why is his discography as a rapper so much different?)
- Treach (all within Naughty)
- Sticky Fingaz (all within Onyx)
- CL Smooth (do 2 classics outweigh a decade of good to great?)
- Fat lip (Pharcyde)
- Cam’ron (obviously a star, are his best 2-3, albums better than Gibbs)
That's 40% of a 54-man list that's arguable, half of them are getting credit for group accomplishments. You're saying stardom isn't necessary but in order to avoid being shut out of the Top 50 by most or all of these artists that's basically what's being asked.