Apparently I worded my first sentence wrong and you didn't bother to read longer than that. Apologies.
I just want to reiterate: DOM objects do have properties, because they are JavaScript objects. You make it sound like they have properties because this is something the DOM API set.
And unfortunately this is only the case for some special HTML attributes, not for all of them.
I think you missed a couple of bits in the article:
> the above only works because Element has an id getter & setter that 'reflects' the id attribute … It didn't work in the example at the start of the article, because foo isn't a spec-defined attribute, so there isn't a spec-defined foo property that reflects it.
This is where the distinction is made between merely setting a property on a JavaScript object, and cases where you're actually calling an HTML-spec'd getter that has side effects.
The whole "reflection" section of the article is dedicated to how these HTML-spec'd getters and setters change the behaviour from the basic JavaScript property operations shown at the start of the article, and how it differs from property to property.
