> The principle claim of this essay is that groups never change their viewpoints.

I understood that the principle claim is that groups never admit publicly that they were wrong. Maybe in reading to much into it, but it is the interpretation I've got. They can, and actually do change, but it is always a "path of victory". And in the few cases that they admit they were wrong is to gain an advantage or when they are forced to: To appear humble, to pivot to a trending opinion before the "other side" do (and usually after a huge pressure).

We have several examples of this: Microsoft with Linux (now Linux is trendy, they want to embrace the developers that code on Mac, and so on), Germany after WWII (decided by the allies in the Postdam conference), or any political party that ever existed.