Totally unknown people randomly met on IRC in 1994/1995 would send you CDs of their own music, strangers from other countries would invite you to come and stay a couple weeks at their place (that existed again for a while at the beginning of Couchsurfing), etc.
The level of trust and friendliness was incredible: There was maybe 0.1% of the population online and we were in awe of this new world.
I find that HN roughly equates to that 0.1%, and there are definitely some other high quality corners of the internet where enthusiasts of whatever topic can have excellent discussions, but it's tough to find them among the ever-increasing noise.
Now that roughly everyone is online to some extent, what's the next frontier -- what can provide that sort of hidden community? I don't know that "power user" or "computer nerd" will ever be the means of gatekeeping that it once was, so what's next?