At this link there is the article where M.B. Petersen (and collaborator) gives a more precise notion of the question behind Myth 2 ("Does social media make people hateful?")
https://psyarxiv.com/hwb83/
I haven't formed an opinion yet, but I'd be curious to hear from anybody who has one. (see among other things how they test for a "hostility gap", page 16).
I appreciate Matthew Green's reminding cryptographers and security researchers that _your research is plausibly not neutral_ and that misuse is not just a "side effect" at times, but it is inherent in the type of work you are proposing.