For me, what triggered it was noticing several startling graphs that all seemed to show a) something sudden, b) at the same time. I started collecting such graphs. It appears the author of this website has done the same. Note that all the "commentary" is embedded in the images - there's no indication that the webmaster has any agenda beyond mine (although the various graph publishers might).
I don't really understand your question about throwing out graphs that don't show a phase-change. There are infinite unrelated graphs. "But, your honor, consider all these photos of my client not murdering the deceased!"
> I don't really understand your question about throwing out graphs that don't show a phase-change. There are infinite unrelated graphs.
Unrelated in what sense? Your example seems a bit of a straw man. What other graphs of economic activity and change do not show a significant and sudden shift at ~1971 (is what I think the parent is asking)?
I don't really understand your question about throwing out graphs that don't show a phase-change. There are infinite unrelated graphs. "But, your honor, consider all these photos of my client not murdering the deceased!"