In general I don't like statements like is. Sure if you look hard enough, or generalise enough, you can make any plot fit into the archetypes. So while they might not be wrong they certainly arent all right, in my opinion.
One could write a romance story with no elements of the 7plots, but analysis could point out that getting the love of your life is a rags to riches story or a quest/journey, and I call bull. With enough time i could find a strong link between the little mermaid and a christmas carol (or insert two random titles) If i generalised enough.
What about the hobbit? Rags to riches? Quest? Tradgedy? Comedy? Return from voyage?
I think sweeping generalisations like this are a very simplified way to classify things that don't need to be classified and i struggle to put into words why I disagree with things like this so much... Uh, but I do
It's the same reason I challenge the vast majority of the psychoanalysis fields I think, there are so many variables that get swept under the rug to make the individual/story fit neatly into a pigeon hole, when the reality is every person and every story has a hundred different layers that make up who or what they are.
Sure some of these plots will be classic rags to riches and quest narratives, but back to my romance example above, I don't find the 'quest for love' the same as the 'quest to slay the dragon'.