It was the direct ancestor of today's VST/AU/AAX/etc synth and FX plugin market.
I really disagree about it as a direct ancestor of the contemporary plugin API. These have always run on the host CPU, not dedicated DSP chips (excluding of course Digidesign's original ProTools model, but that was DSP farm rather than just a chip).
And the sort of DSP that was being done on the Cube DSP was being done before the Cube too.
When NeXT was folded back into Apple, the audio classes eventually became (more or less) the AUs in MacOS.
An abstraction layer made it possible to run natively, or on internal DSP, or on external DSP. Aside from Digi, Waves, Universal Audio, TC Electronic, and Focusrite all made external processors that used the AU/VST interface. (UA still do, although recently they - at last - also started offering native versions of some of their plugins.)
Waves in particular, who I worked with in the 2007-2014 era, did not do this until Linux got into shape to allow them to build plugin/DSP servers.
That's like saying "computing in the 80s was all about the home computer market, if we exclude the PC". ProTools was the biggest name (and quite close to a monopoly for pros at the time).
ProTools had a separate box that had the DSP farm in it. There was nothing particular unique about that (at the time) (though running a DAW on it was definitely novel when they did it).
