So I was really suspicious of this, both because it seemed too tidy and the citation to "Kendall Pearson" was suspect. I recommend the cited paper by Hurlbert

So I was really suspicious of this, both because it seemed too tidy and the citation to "Kendall Pearson" was suspect. I recommend the cited paper by Hurlbert & Lombardi (2009), which makes a lot more sense and explains things more clearly. The actual discussion in that paper claims that Kendall was relating a story told to him by Fisher, about Pearson's defense of copyrighted tables. So Pearson publishes books of tables, which were expensive to print at that time, and is defensive of them, leading to challenges for Fisher, who relates this to Kendall. The claim that copyright played a role seems partially true (if you believe Hurlbert & Lombardi, 2009, which I do). Hurlbert & Lombardi make clear the dichotomous thinking about significance, use of p<.05 etc, was prevalent before and the copyright obstacles, but the copyright obstacles may have reinforced the trend further. It's pretty clear standard significance thresholds (.05, .01) were being thrown around in various forms for other reasons having nothing to do with copyright, but the copyright issues kinda nudged things further in that direction.