These articles are talking about the reward loop of getting new content every time you refresh, and you're misrepresenting that to presumably make a point about pull-to-refresh, which is completely unrelated.
Article [1] doesn't mention pull to refresh; Article [2] mentions pull to refresh in the context of email;
There is no dark pattern here; yes social media itself is made to be addicting. Pull to refresh is an intuitive UX pattern that can either assist in enabling the addictive behavior, but it is not the cause of it, not only to be used in that kind of scenario.
In a bank robbery, if you are driving the getaway car you are not techinically the cause of the robbery, but you sure as hell enabled the robber to get away clean.
Wow, hadn't realized it was a dark pattern. After thinking it through though, is it really a bad way to update a page? I realize we have the tech to easily dynamically update content without user consideration, but that ends up leading to people clicking on the wrong thing (the order suddenly changed on them as the finger went down).
So given that an explicit refresh button either takes up screen space or is another action (say full page refresh?) should this really be considered a dark pattern if you're say, in your own inbox?
It's a pretty big misrepresentation to claim that pull to refresh is a problem, when the core of the issue the "dynamic content" as you put it. It's like blaming weight problems on good cutlery.
Yes, it's a tool that can be abused in the right (or more aptly, wrong, I guess) circumstances, that doesn't make it a dark pattern in other situations.