Kris on Twitter asks that question. I have a few hypotheses, none confirmed by any hard data, other than my “lyin’ eyes”:
1. Twitter exists as a kind of parallel truth/falsehood mechanism, and it is encroaching on traditional academic processes, for better or worse.
2. Hypotheses blaming people or institutions for failures and misdeeds will be more popular on Twitter than in academia, but over time they are spreading in academia too, in part because of their popularity on Twitter. Blame makes for a more popular tweet.
3. Often the number of Twitter followers resembles a Power law, and thus Twitter raises the influence of very well known contributors. Twitter also raises the influence of the relatively busy, compared to say the 2009 world where blogs held more of that influence. Writing blog posts required more time than does issuing tweets.
4. I believe Twitter raises the relative influence of women. For one thing, women can coordinate with each other on Twitter more easily than they can in academic life across different universities.
5. Twitter can damage the career prospects of some of the more impulsive tweeting white males.
6. On Twitter is is easier to judge people by their (supposed) intentions than in academia, so many more people will be accused of acting and writing in bad faith.
7. On Twitter more people do in fact act in bad faith.
8. Hardly anyone looks better on Twitter, so that contributes to the polarization of many professions, especially economics and those professions linked to political issues. Top economists don’t seem so glamorous any more, not even in their areas of specialization.
9. Academic fields related to current events will rise in status and attention, and those topics will garner the Power law retweets. Right now that means political science most of all but of course this will vary over time.
10. Twitter lowers the power of institutions more broadly, as institutions typically are bad at Twitter.