If you read the article you'll see that they used 6 categories. One of them actually being "pointless babble". If you ask me, 5 of the 6 are actually pointless. Only 1 of them (news) would be worth reading. So, while 40% might be "pointless babble", I'd say 90% would be just pointless.
A study reveals that more than 40 percent of Twitter's tweets are 'Pointless Babble.' So what were we expecting? Why should self-published content to be different than, for instance, conversation?