Even before the Tweetstorm phenomenon, Marc was favoriting, RT’ing, sparring with people, @replying to random folk who reached out to him. In the first 2 weeks I even saw a few people on Twitter say, “Is that the real Marc Andreessen?” He was writing to people. Many people. Any people.
He was doing what many public figures fail to do on Twitter: He was engaging.
This to me is the real magic of Marc Andreessen on Twitter. Not replying to anybody on Twitter is like speaking on stage at a conference and then sneaking out the back without shaking any hands. People want to see you speak but they REALLY want to meet you. Even if just for 60 seconds.