They should probably mention the Casio CZ-1 next to the DX-7. It was a similar sort of digital synth (just barely skirting the Chowning patents on FM synthesis that Yamaha had exclusively licensed with its “phase distortion” synthesis) and used by bands like Depeche Mode.
A few years later, when both RAM and ROM got cheaper, sample-based digital synths like the Roland D-50 and the Korg M1 arrived, and brought a new kind of sheen, as evidenced in not-quite-real string sections, slap-bass and that Italo-house piano sound.