I never cared about structural editors because the argument always seemed to be that being able to ruin the parse (going from a state where it parses to one where it doesn’t) with your editor is bad. Because I don’t care: I want the supreme flexibility of going from state A to B through some ill-formed textual editing much more than I want to be protected from ending up in a bad parse state, since syntax errors are o…
Seems like the author agrees with you (albeit in a different article):
> … the traditional structural editors do tend to impose some limitations … But these are not the inherent qualities of structural editing. This is just the way someone chose to implement it. So, when I say that Rune provides seamless structural editing, what I mean is that the other kind of choices are possible: the kind where you are editing as if the structure is only apparent, but not in your face, and so, it's just like there are no seams.
— https://project-mage.org/the-power-of-structure#orgeb59167