[paulmd]

There's value to having someone with a deep understanding of a topic who can follow leads and investigate, construct a narrative out of disparate facts, and then deliver it compellingly. I guess it doesn't have to be a journalist, but you will need those same traits and I don't think that's a particularly common combination without specific cultivation. Clickbait and press releases obviously don't deliver that either, of course.

The hardware to run a site has become much cheaper, but at the end of the day it still takes a lot of hours to produce content and cultivate a community. There's a huge amount of business roles and work that you're glossing over there - from admin to overseeing content production to developer. Peer-moderator type systems like Reddit have lots of issues - even at the best of times they have a bandwagon effect that shouts down statements that are unpopular with the masses, and at worst they are very susceptible to sentiment manipulation like voter rings. I don't doubt there are "viral" marketers that provide social-media promotion services.

I'd also point out that looking at specific examples can be deceptive. Slashdot is late in its life cycle and the community has clearly decayed from its glory days. Digg probably doesn't need as many servers now either. But you'll never run a top-10 website on a Raspberry Pi - or any site whose performance you care about, for that matter.