I think that you're missing the point, which is, at the time, when fashion was quite fussy and full on, she looked different, pared down, simple, defining the clothing rather than letting the clothing define her. She chose and combined pieces in a way that became a signature style. As I said earlier, it's not my style, but in her hands it was a confident and unapologetic look and she rarely varied from it.
And what is your thing with SAHMs? It's rude and weird and unnecessary. Did you know for certain that every single woman at the school run dressed like that was a SAHM? Not a single one was going to an office? All of them were putting on identikit white shirts and cashmere and camel hair for the school run?
wore very highly tailored skirts and jackets from Pauw in Amsterdsam and Lillith in Paris , but the sort of tailoring that came with instructions on how to button/ wrap etc [ both brands have gone more mainstream now] I definitely wasn't wearing "classic neutrals"
A lot of people jump on bandwagons and think they're edgy and fashion forward. That doesn't make it true. I doubt anyone would look at something from 'Pauw in Amsterdam' and say, oh, that's classic @IHaveAlwaysLivedintheCastle, because it's not a look, it's an outfit. But you could look at a combination today and say, oh, that's a classic CBK look, which makes it iconic.