I wonder if the author had had any exposure to the PLATO system at the University of Illinois. By 1974 it had a very active online community with email, chat and, yes, forums. Very active forums of every kind. And people did with them pretty much all of the things that happen today on the internet - but no annoying flash videos. :-) That's a joke - 1200 baud couldn't do that.
Anonymity was less available on PLATO, but there were a few ways to obscure one's identity, and a few of PLATO's group note files (forums) allowed anonymity. Google PLATO and find the motherlode of prior art.
As I recall, Demosthenes, was the designated troll in the arrangement and Locke was the voice of reason authored by the characters with the most ambition.
Another prediction from the book that caught my attention was the established use of DNS and universal email addresses or at least the implication that an email could be addressed to any user without knowing the address of the server, the path to get there or the mail-provider of the recipient. The novel was written during the formative age of the Internet and the author did a pretty good job of predicting how it would become part of daily life.
Just like Demosthenes and Locke winning politically with their technology, US Presidential races are often won by the candidate that masters the new communications technology. Lincoln won with only a plurality, in part due to his mastery of the then-new speaking circuit. Roosevelt with radio and his fireside chats. Kennedy with Television. Regan with sound bites. And arguably in the last election, Obama with the intersection of social media and Big Data for a last-minute get-out-the-vote that pushed him over the top in the final hour.