Beyonce definitely blackballed:
BC Jean: She wrote If I Were A Boy with her producer. The producer played it for Bey's team behind her back. Bey's team wanted the song. Bey simply re-sang BC Jean's vocal, but ended up with songwriting and production credit. BC Jean cried foul to the media. Bey's people put some money in her pocket and she changed her tune in the press, calling it a misunderstanding. But it was too late.
Rich Harrison: Rich Harrison was red hot because of his productions for Amerie. Beyonce wanted that sound. She picked a track she liked and told Rich to write the song while she was gone and have it done when she got back. Rich completed the song. Crazy In Love was a smash and rolled out Bey's debut solo album perfectly. Even though he wrote and produced the song, Bey still got writer and producer credit. Rich told this story to the press. No more Rich Harrison on ya radio.
Boots: Boots wrote and produced the majority of the Beyonce self-tiled album. Beyonce was considered a big improvement over the 4 album by fans and critics. When the public saw Boots' numerous credits on the album, people got curious about him. Someone found his Soundcloud account. Boots forgot to remove the demos for the Beyonce songs from his page. The demos also had identical lyrics to the finished versions. Like everyone else, Boots was forced to share writing and production credit with Bey. So with the public finding the fully formed demos, it poked further holes in the narrative that Beyonce was not just a singer but a competent songwriter and producer in the vein of Michael Jackson. The fact is that in order to secure placement on a Beyonce project, you must give her fake writer and producer credit.
Keri Hilson: Been explained