Earlier quoted context omitted.
I had the same reaction of "no market" from the article, but on reflection I suggest turn it around: instead of thinking of it as "a programming environment", think of it as a specific application first, which has customization added to it, and eventually becomes programmable. Seeing it this way, such environments are very common - they are just not presented as "programming environments". And that may be what is dif…
If you look at it as purely customization, yes, there's a thriving market. But the author is specifically looking for something that creates a world 'where the distinction between the “use” and “programming” of a computer has been weakened'. And the point is that those are fundamentally different activities. There's only a very small intersection that needs the simplicity of "use" and the complexity of "programming".…
In real (non-coding) life, there's usually overlap, of "adjustments". e.g. you're cutting tomatoes with a knife, and adjust the knife's angle, or your grip, or move the tomato, spin it on a vertical axis, rotate it, try sawing vs slicing, maybe change knives, etc. Perhaps you exclaim "This is the best knife for tomatoes!" and resolve to use only it henceforth. But many of these adjustments are unconscious, and part of everything we do. Is it "operation" or "design"? I think it's fuzzy in practice; we often chip away at things as we learn and adapt.
True, in software, there's usually a sharp line between user (operating) and programmer (designing). Customization crosses that line: macros, templates - even, hiding menus you don't use. Is hiding a menu "programming"? While not turing complete, it's a step closer to it.
I agree there's not much market for the combination, in itself. Programming is so accessible these days, if you want to do it, you just do it. Probably starting with HTML "programming", then Javascript or PHP. It even looks like a real website! It's like hypercard, but global.