Why does the WWE seemingly not push the black wrestlers when it comes to the WWE Championship belt?

I am fully convinced about this, and before you give me your answers consider this. Firstly, other than The Rock (which we'll get to in a sec), no black person has ever won the WWE championship. Also, no black person other than Booker T has won the World Heavyweight Championship. There have been 4 ECW champions. However, the black wrestlers do get the IC and USA belts quite frequently. I just want to know if there is something wrong with the writers, or do they think that black wrestlers can't carry the company? Also, about the Rock...He's a legacy. His father and grandfather both wrestled for the company so he had to get a large push.