We can also compare with our parents and the amount of friends they have and meet. They don't know how to use the internet enough and are not used to treat internet friends as friends, so they are a very good control group. How much time they spend with friends, beyond the rare birthday parties? How often do they call each other? Or the famous "going to church" argument - church which is once a week and takes 2 hours where most of it you don't interact with anybody just sit and listen. Plus after a certain age most of their old friends are gone and that loneliness hits hard because there's no replacement process.

Enough of my adult life occurred during the time when significant chunks of population, often the overwhelming majority, were offline. I could very well compare. Somebody's reachability online, or at least via email or fidonet messages, radically improved the chances of continued contact and regular face-to-face meetings, whether it originated offline or online. The world not mediated by online connectivity was radically narrower. It required physical proximity (usually the same neighborhod, sometimes the same city), and exchanging phone numbers, an approximation of "online", was crucial for most longer-term relationships.