You’re using “mainstream” in place of “safe and popular.” And the categories that have been Billboard-dependent have generally been just the Pop and Rock categories until rather recently.
Look at the list of rappers with the most grammies.
1. Jay Z – 22 Grammys (1 Best Rap Album);
2. Kanye West – 21 Grammys (4 Best Rap Album);
3. Eminem – 15 Grammys (6 Best Rap Album);
4. Kendrick Lamar – 13 Grammys (2 Best Rap Album);
5. Lauryn Hill – 8 Grammys (1 Best Rap Album);
6. Dr. Dre – 7 Grammys (0 Best Rap Album);
7. Outkast – 6 Grammys (2 Best Rap Album);
8. Lil Wayne – 5 Grammys (1 Best Rap Album);
9. Childish Gambino – 5 Grammys (0 Best Rap Album);
10. Drake – 4 Grammys (1 Best Rap Album);
11. Macklemore – 4 Grammys (1 Best Rap Album);
12. Will Smith – 4 Grammys (0 Best Rap Album);
13. Chance The Rapper – 3 Grammys (1 Best Rap Album);
14. Diddy – 3 Grammys (1 Best Rap Album);
15. T.I. – 3 Grammys (0 Best Rap Album);
16. Ludacris – 3 Grammys (1 Best Rap Album);
17. Nelly – 3 Grammys (0 Best Rap Album).
Aside from Lauryn Hill and kendrick lamar, all these artists were considered "safe and popular" at their peak. The grammies have always been about mainstream popularity.
Why is this shyt still taken seriously?