There were plenty of us there who were accidental visitors, curious kids who found ourselves in this interesting world. Kleinrock mentions this briefly in the original article, but there was a high degree of trust and optimism on the early internet, and if one was technically inclined and a little outgoing and generally a good egg, it wasn't hard to get an account somewhere.
When I first logged into MIT-ITS around 1982, coming in over dialup as a teenager calling a modem bank near the Pentagon, the login-failed message said something like, "Sorry, that username does not exist. Would you like an account?" It was RMS himself who gifted me (and a lot of others) a free account for the asking.
It's a hard thing to explain to people who weren't there -- I think this is why so many people in this thread see Kleinrock as naive or worse. My girlfriend never believes me when I try to explain the early internet; it seems an impossibility to her, as if I was talking about some pre-historic hunter/gatherer culture.