There's a big difference between having some people online and having most people onine. That's a difference that appeals mainly to businesses, now the audience is larger. But there's another difference between having most people online and having everybody online. The advantage of having everybody online is that in your social group, if everybody is online, then you can take it for granted that you can use online tools to coordinate the life of that group.
Small social groups have very high density. In a group of five or six people, pretty much everybody has an interface to everybody else. That's a lot of interface. If even a couple of those interfaces can't be bridged by email or instant messaging, then people will default to the most inclusive possible technology, which prior to the Internet was the phone.
If you were under 35 in the year 2000, and you made more than $35,000 a year, you were almost certainly online and so were your friends, and you could start to take it for granted that you could use the Internet to coordinate your business life and your social life. You could use it to coordinate visits to church, group buying pools, anything that involved a group. Suddenly it became possible, and not because the technology was in place; the technology had been in place for years. It was because the social density had finally caught up with the technology.