You mentioned the visually impaired in the article. For them, visual mediums are pretty meaningless, completely so for the blind. Their imagination can let them paint their own visuals, create and explore their own world triggered by a good work of sound design. Like the way a piece of music has a beginning middle and end so should a stand alone piece of sound design.

And I guess if you’re just talking about single sound effects (maybe a second or two long) go full on Men in Black with them. Try and make them complete worlds within worlds. If the listener can mentally re-explore a sound each time they hear it then great. Once it is tied to a visual medium the listener will hear what it is intended they hear and thats exactly what should happen. But when heard solo they can focus in on the beginning middle and end of that sound, really explore it.

On the subject of the visually impaired try this exercise I used to play with when I was a kid. Be blind for an hour. Not driving home from work but one evening turn the telly, computer, phone etc all off and close your eyes. Just listen. The details you will notice will surprise you.

Recording or generating new source material or reusing existing stuff, manipulating while performing/recording or doing it in post but without a specific intended use in mind is just the best part of what I am allowed to do when I work :-).

If you just work on sound to picture and to fulfill special roles then I find that “you” are likely to limit your creativity because as soon as you think you got the sound that works for what you need you are most likely to stop and keep chugging away.
So I find doing “pure” sound design whenever I get a conceptual idea extremely fulfilling. And as long as you produce enough material then it is quite likely that when you need that special sound there will be enough variations and different length and starts and stops to make it all work.

I’m not sure I like the word “pure” though. It sounds like it is better and “more pure” than any other type of design work, and of course it isn’t in itsef. But then OTOH you need something to explain the difference so…

And oh, there was a question.
What is the “essence of pure sound design”?
I couldn’t care less in a philosophical way. Defining that can only create boundaries or limitations that I’m not really interested in.