I think you make a very good point - which is that in the bigger picture, music is inherently evolutionary in a way that generative music isn't.
Having some experience with generative apps, I know that they absolutely do not make music spontaneously. You have to invent them, build them, and tune them - all by hand/ear.
It's more like building an instrument - i.e. a machine - and tuning/debugging it than cultivating a garden.
Music as a whole is much more free. When it's loose in a culture, it can evolve in weird, unexpected directions that no individual composer would ever be able to imagine, and no app today would come close to copying.
I'm a couple of years into playing with generative music, and one of my big problems is finding prior art to imitate...
My personal feeling about Eno's approach is that it almost deserves a different label than "composing" - maybe "incubating" (you know, like a startup incubator). For me, and I suspect for a great many music lovers, "composing" implies a process that may be evolutionary to some degree but is still overseen and directed from beginning to end by a particular artist. Contrast that with the case of traditional music from $REGIONAL_CULTURE where the process is more truly evolutionary as songs are passed from one generation of bards to another.
(I don't mean to say that Eno's approach to making music is somehow less legitimate than any other. It just seems better described by some other word.)