This is true, but I never thought of Agatha Christie as one of the good examples of it.
I think that the reason that mysteries are so popular nowadays is that they have to have some structure and an ending that makes some sense. Whereas modern 'serious' fiction doesn't seem to be required to have a plot at all. In a detective story you have to actually tell a story, not just throw some random stuff on the page and hope people think it's deep. Or maybe I read too many New Yorker short stories. (And that's only one by accident every few years - still WAY too many.)
HA!
I agree totally (and I still read almost every short story in the New Yorker). That's one of my main criticisms with modern fiction -- it's gotten so stylized that there's no there there. It's all well and good to write prose that is beautiful and innovative -- I admire a good sentence as much as the next guy. But if the action conveyed is so tiny or internalized as to be undetectible that just unsatisfying. I want style
and plot. (I'm looking at you William Gibson...)
Is the Detective Story the purest form of storytelling? No. I'm not sure what it means to be a pure form of storytelling? I suppose the purest form would be a first-person narrative in which the storyteller is also the narrator told in chronological order (i.e. This happened to me, then this happened to me, then this...) Would that be more like a "Journey Story"?
In a Detective story the detective is a stand in for the reader. The essential plot details are revealed to the reader through the detective, so that adds a level of complexity to the story. And the contrivances discussed by which authors present some details and hide others in order to create dramatic tension, well that's another level of complexity. So I don't think a detective story is really very "pure" at all.
Which is A-OK with me. A good detective story is extremely satisfying to read. A good detective story requires a good detective. I think getting to know those characters is more than half the fun of a detective story. It's hard to come up with a truly new plot but interesting new characters are all over the place.
Two of my favorite detectives: Edward X. Delany and Judge Dee Jin-ji