Question: While I'm sure economists have been studying this effect for decades, or maybe even way longer for all I know, it seems like this metric has been popularized as the key thing everyone looks at just in the last decade -- after the last recession that we had. Given the popularization, any chance of an increased observer effect? In either direction, I mean, positive or negative.
no. also there is no "popularization." it's just a historical pattern.
It's completely legitimate to question whether this increase in publicity for this one metric might be causing it to be less useful.