It could be argued that the DX7 had a significant negative musical contribution. Oodles of sounds at the expense of musical expression. The musician became alienated from the process of making the sound. The keyboard player's job moved from playing the piano or organ to coming up with all the accompaniment parts that aren't guitars.
And the DX7 was way too difficult to program. Sort of like trying to solve a Rubik's Cube; you can be one twist away and not know it. And since whole point of synthesis was for the musician to explore and tweak their sound, the DX7 was sort of an anti-synth.
That said...
Maybe it was an accidental choice of words in the article, but I would also say that the DX7 was, indeed, one of the most important advances in terms of musical engineering.
Given 1983 technology, it was very difficult to implement digital audio filters, which require millions of multiplication/accumulation operations a second. The microprocessors of the day were not up to the task. TRW offered a 16x16 bit multiplier chip, but it cost around $300 for the chip alone (!!!) and required significant support circuitry.
FM synthesis, as such, was not new. The Buchla synthesizer featured it in the 60's. John Chowning refined the concept, moved from frequency to phase modulation, and brought FM into the digital realm.
Then some smart folks realized that FM synthesis could be implemented entirely in add and ROM lookup operations, which is downright easy in 1983 technology. Then they refined FM some more so it could produce a wide timbral range from the single engine.
That's the impressive part of the DX7.