This man made it his life's work to ruin three, I repeat, three kinds of music-- and he succeeded.
This is the guy that decided it would be a great idea to graft jazz, rock and roll, and latin american music together in a hideous, Frankenstonian Cerebus of a genre called "Jazz Fusion".
So awful was his power that he was able to convice Miles Davis that this was a good idea. Granted, Miles was on a lot of heroin at the time, but still...
What's worse is that this is directly responsible for the abject horror we know as "soft jazz". And because of that, RWHN.
I want to go back in time and crush this man's fingers with a 10-pound hammer.
I'm a little uncertain about your chronology here...lol....
During the 1960s, the middle aged Miles Davis was facing a potential career crisis. Jazz was beginning it's decline in popularity, Miles wanted to be 'cutting edge' but did not want to join in with the 'New Thing' (aka Free or Avant Garde jazz). So, he opted initially for a middle ground by bringing in a bunch of younger players (Hancock, Shorter, Carter & Williams) who could play all the mainstream jazz material (blues, ballads & standard songs) but had an ear to the kinds of things going on with Ornette Coleman, Coltrane quartet etc. (Snarky side note is that Wynton Marsalis states that at this point, Miles had peaked technically and basically wasn't up to the music that his younger cohorts were capable of playing)
Having gone as far with that as he could, Miles was looking for something new, especially if it carried a larger paycheck. He really liked James Brown, Sly Stone and Jimi Hendrix...(note that he liked Jimi but not the rest of the Experience who he thought were terrible.) Add that to a massive amount of cocaine, the fact that music companies were giving him free electric pianos and that Miles was fucking younger women who were into rock & R&B and HEY PRESTO....FUSION was born. It's when Miles' hair started to recede and he gave up wearing Brooks Brothers suits in favor of bell bottoms, massive sunglasses and stuff with tassels.
Everyone who had a career in 'fusion' went through Miles' band first:
Herbie Hancock ---> Headhunters
Joe Zawinul, Wayne Shorter ---> Weather Report
Chic Corea ---> Return To Forever
John McLaughlin ---> Mahavishnu Orchestra
Tony Williams ---> Lifetime
George Benson ---> gave up straight jazz in favor of making pop & soul records.
All of these people had established careers playing acoustic jazz, then they played with Miles in the 60s/70s following the gradual dissolution of the 2nd quintet. After their time in Miles' band they all went and made fusion records of their own. Miles made
his pianists play the Fender Rhodes. People like Hancock actually liked technology so he rolled with it. Keith Jarrett on the other hand thought it was godawful, hated playing it and the music he did with Miles, but he just wanted to be around him. Unlike the others, he did not make a fusion record but went back to his regular piano and that weird, squeaky, scat singing noise that he makes when he plays.
So, I contend that Mr Corea did not invent fusion. Miles Davis having a mid-life crisis created fusion.
I don't know who to blame for 'smooth jazz' but I don't think that can be laid at Mr Corea's door. What he does need a bitch slapping for however, is his insistence that his being a big old Scientologist has negatively impacted his opportunities as a performer. Uhh....Hollywood much?
Should you get that time travel thing working, to prevent the existence of fusion, you'd have to check Miles into rehab, get him to date women his own age and explain that he can't ask Columbia records for huge salary raises just because he wants them.