If you were to modulate frequency, well first of all you'd have to define a reference point or you'd just get glitchy sound. In practice that means most FM implementations just have a highly oversampled single cycle of a sine wave in memory, and it's the speed at which the sample pointer consumes the looping sine that's set to correspond to some frequency, and then that value is modulated. In other words, phase modulation.
The DX-7's lack of patch-cord 'programming' ...replaced by 32 instantly-selectable, well-conceived preset patches in RAM ... was essential in 'democratizing' synthesis. Because it wasn't easy to make new patches, it also jump-started the patch-creation business.
The 16-note polyphony also didn't hurt.
" in 1986, it was used in 40% of the number-one singles on the US Billboard Hot 100." -- Wikipedia
Early electronics from Japan were often seen as inferior products compared to the American and European products (RCA, Westinghouse, Philips, Telefunken, etc). Japan of yesteryear was the China of the 1990s and early 2000s, some decent stuff but a lot of cheap clones. Now, China makes everything so that analogy falls apart today. The 1970s oil crisis was one of the major events that helped bring Japanese goods into a better light, Japanese cars were absolutely killing the domestic automakers on fuel efficiency and price and rather than engage protectionist tariffs (Chinese EVs today, hmm?), they forced the domestic automakers to try harder. This change in public perception helped give a real sales boost to other manufacturing sectors, like consumer electronics which in turn helped drive innovation in a very short time period. That's not to say Japanese product was junk in the 50s and 60s, there were a few dominant players of quality products (Sony) but like Chinese manufacturing today, there was still a lot of cheap junk.
Did he? Wasn't there New England Digital (NED) with the Synclavier which had FM on the market before Yamaha? Are you sure Chowning gave licenses? I would rather expect that this was the Standford administration's business, not Chowning's.
Then came Yamaha, who saw its potential, and made a fortune with it. So did Stanford. That patent became the second most successful patent Stanford ever had until it expired in 1996 (by now obv the university has had way more financially successful patents).
It secured Chowning his tenure; the university probably wouldn’t have prolonged it otherwise. Quite an incredible story the whole thing.
Even more with Chowning's background as a musician, not an engineer.
> Multiplying sounds just sounded too ridiculous
Is this really the "official" reason, or your interpretation?
AM (amplitude modulation) is multiplication. When you do it fast, you get what's commonly called a ring modulator.
Can't vouch for this but from what I've read the 2025 remake (Highest 2 Lowest) is...not good.
E.g. Akai working with Roger Linn on MPC and Chris Huggett on the S1000 sampler.
Or Dave Smith working with Yamaha and Korg on physical modelling and wave sequencing.
You can buy a full FM synthesizer on Temu for very little.
https://www.youtube.com/watch?v=988jPjs1gao