Michael never sabatoged the careers of his brothers. Though Michael was the first brother to release a solo album with Got To Be There in 1971, Jermaine was actually the first Jackson brother to have a bonafied solo career when he left the Jackson 5 in 1976 when Michael was still a teenager and didn't have the power he would have from the 1980's onwards.
Jermaine's was hoping to be a Marvin Gaye type of artists, and he had a secuirity most artist don't have ie he was the son in law of the president and owner his label Motown, Berry Gordy. Jermaine may or may not have got the promotion he wanted, but his career never really took off and he had a couple of minor his in the charts. I know he felt that Michael could have clout to have had his 1984 duet with Michael, Tell Me I'm Not Dreamin (Too Good To Be True) to have been released as a single. As Jermaine said that was his only ever shot at having a No.1 single. I think he may have carried a grudge against Michael for this until the 1993. Now he's very protective like he used to be.
Michael and Jermaine are really the only Jackson brother to really have a solo career. As far as I'm aware Jackie only ever released one album, and that was with Motown in the early 1970's. Marlon (I think) only released on solo album being Baby Tonight in the late 1980's. And Randy also (I think) only ever released one album, and I think maybe the same with Tito (not sure if he has ever made an album).
Apart from Jermaine, I don't think Michael's brother wanted solo success as much as people would like to think, I don't see that drive in them as LaToya has released more solo music then them, and she didn't have the credibilty being in The Jacksons/ Jackson 5 as part of her career.. My view his Jackie, Tito, Marlon and Randy preference is being in The Jacksons/ Jackson 5. Michael would have been very happy if his brothers had solo success. What I always wonder is why Jackie and Randy never went on to be producers and songwriters for other artists, because those two are amazing talents in the studio. Your Ways, from the Triumph album which Jackie wrote/ composed is one of my all time favorite Jacksons songs. An amazing song !