Recently some spinoff/copycat groups have also sprouted up. There’s a “Dull Men’s Forum”, and a “Dull Men’s Fun Club”, for example, which post similar memes. And a “Dull Women’s Club” as well (even though I also often see women posting in the Dull Men’s Club, I suppose women on average have different sensibilities about where to draw the line between dull and interesting).
I view this as a sign that the group has become too popular and lots its “edge” (which in this case was its authentic dullness), and now is just a place for farming likes and impressions from the broader FB community. A lot of it is quite derivative of other popular posts - “what is the purpose of this thing I found in my hotel/new house/grandma’s house” posts seems to be a really common theme, for example.
Some of these are _pages_ that post content stolen from "dull" groups or from other groups that are thematically not far off, like Aldi fan groups. As your view includes pages that are just mass-theft operations seeking Facebook payouts, you have selection bias.