I think you're going to have connect a lot more dots than that to prove that type of conspiracy. These awards are heralded year after year because of their reliability in giving people what they expect out of an award, whether they're forward looking (for predicting future success) or more backward-looking. There is some flexibility in how people judge deservedness for them.

You can at least concede that when it comes to Toni Morrison, its not like she only won a couple of isolated awards. She won a long string of them, and is one of the most decorated American writers of the last 80 years. One of her books, Beloved, was made into a movie by Oprah. There are plans to make a second book (Sula) into a movie or series as well.