Well, you should consider the possibility that you and your coworkers are not representative of academics more generally. In my research field Twitter is quite matter of factly really big. Also note that this was just an example showing that there are more areas where Twitter is doing really well than those that OP listed.
I'm talking about tens of thousands of people not individual cases. Pretty much every university, non-university research institution, and funding agency have active Twitter accounts. In my experience, most departments, and labs also have twitter accounts, not to speak of individual researchers. Jobs are found on Twitter, careers are made, new collaborations start there. I'm talking about tens of thousands of people who are highly active on a daily basis, whereas /u/kleiba was referring to himself and some unspecified coworkers which I interpret to be his lab mates.
