I suppose it's easy to assert that a site is immune to ES when it's in its infancy-- the argument made here is that HN's niche hardcore basis protects it, but the same argument could have been made for reddit 5 years ago, a case which they curiously use as a token example of ES. I think the takeaway here is that only intentional and deliberate measures to protect against homogenization of a community will work -- and these are often less egalitarian by design.
Agreed. Those deliberate measures are perfectly executed by both HN and Quora members. They don't let their content be crowd/outsourced totally, they moderate it. And that's what makes HN and Quora stay great.