That hypothesis more or less amounts to the idea that humans who would be nicer to each other in person might feel more inclined to get nasty when interacting with other pseudonymous internet users. The researchers found little evidence for that.
Instead, their data pointed to online interactions largely mirroring offline behavior, with people predisposed to aggressive, status-seeking behavior just as unpleasant in person as behind a veil of online anonymity, and choosing to be jerks as part of a deliberate strategy rather than as a consequence of the format involved. They also found some evidence that less hostile people simply aren't as interested in talking about politics on the internet. [...]
One study [...] found that the most aggressive online trolls may tend to be high in cognitive empathy, which allows them to identify when they're pushing someone else's buttons, but low in affective empathy, enabling them to avoid feeling bad or internalizing the suffering they cause. [...] as platforms have "optimized for connectedness, they have negligently optimized for the growth of mob-like communities connecting around noxious yet identity-defining goals." [...]
Bor told Engineering & Technology that the results supported stricter enforcement of rules against hate speech, as it is "not born out of ignorance" and aggressive people are fully aware of how disruptive and harmful their actions are.
In other news, water remains wet: