The analogy to sound synthesis is strange to me. As both a musician whose primary instruments are acoustic guitars and computer software, and as a writer of poetry, prose and essays. I can’t speak to fears of synthesis obsoleting other music performance, mostly what I’ve heard expressed is snobbish purity that it’s not “real”—either real talent, real music, or real performance. But at the end of the day, synthetic instruments are still instruments. Fundamentally a primitive like a string or a reed attached to something which lets you make sound from it. A “simple machine” in the mechanics sense. They’re not composition synthesis, which is definitely an area of exploration now, and which is more akin to image and video synthesis.

Photoshop conceptually sits somewhere between these two extremes of electronically-aided creation, but much closer to sound synthesis, than what the author is hypothesizing. I can’t even think of a text analogy for sound synthesis as you’ve described. The least nonsensical imagined example I can think of is “this word does not exist” (as in word synthesis), which would be more valuable as a game or a gag than as a tool.