Why was Brian Jones dismissed from the Rolling Stones in 1969?

Brian Jones was dismissed from the Rolling Stones in June 1969 primarily due to his declining creativity and influence within the band, which had been exacerbated by his struggles with drug use.12

While Jones was a founding member and a highly gifted multi-instrumentalist who served as a prime motivating force in the group's early years, he lacked talent for composition. As the songwriting team of Mick Jagger and Keith Richards took creative control of the band, Jones became increasingly marginalized. Additionally, he developed a reputation for being self-centered and difficult to work with, eventually becoming what was described as a "depressive, drug-sodden liability" to the group. He died just weeks after his departure.12