It is necessary for a great discussion site to be founded by an elite person or by elite people, because the core of the site needs to be made of people who both have quality thoughts and express them well. For whatever reason that isn't a commonly found trait, so those who possess it are elite.
That said, it is not necessary for founders of discussion sites to pursue exclusion, and as we have seen on Hacker News, a variety of quality new members are attracted here by the 'elites' and also become good participants. Many, in my opinion, surpass some of the 'et al' in member quality.
I do think some mediocre members come along with, but I see them developed into better members over time, and this gives the community practice assimilating and improving mediocrity. By contrast, TheList will have very little practice spreading its culture so it will be a brittle, barely fruitful community.
So, a community with elite core members can be open and fair to new members while making them into better members and even has the possibility to improve the community over time. A community with less than elite members that practices elitism and exclusion does not do as well even relative to its initial position.
Also, I think it's critical to be aware of correlation versus causation in situations like this. What is causing the "refinement of elite persons" that supposedly turns mediocre contributors into better ones on HN? We can say that people who read HN more than once a week will likely have exposure to something that helps them learn and grow, but that is not due to the nature of the other "elite" people on HN. It's due to the nature of the information presented on HN. I become a better programmer because I am exposed to quality information on HN, not because some "elite" member of HN is doing anything to make me a better programmer. This is a very important distinction, because more often than not, it seems that the "elite core" of HN is under the impression that they are improving mediocre contributors (and claiming victory) when in fact it is the content doing the improving.
There is a very interesting link here on HN called "the elves are leaving middle earth -- the soda is no longer free" (or similar) which describes the kind of "scale problem" HN is having. The management of HN itself is undergoing a very similar transition, from one of encouraging the hacker mindset to... something else.
Most importantly, I have often found that the "elite core" is sanding away the sort of rebellious je ne sais qois that makes a person "elite" -- or a "hacker". Please reference my favorite essay of pg's about "the word hacker". There is visible decay and erosion of the principles expressed in that essay in the daily happenings of HN. I have for years thrown that essay around as a cure-all explanation of why I think the way I do, and it seems an opus of irony that the "elite core" of HN would do well to read it and take stock. You should wonder why a "hacker" like myself is burning through throwaway accounts and getting hellbanned for what amounts to the expression of dissenting opinion. As pg said so eloquently so many years ago -- indeed, a different pg altogether -- a hacker "can sense totalitarianism approaching from a distance, as animals can sense an approaching thunderstorm".
My senses are telling me to avoid HN and its "elite core", to the point that I need to weigh the benefits of staying versus the benefits of never coming back. And that is not a good sign for HN.
I also agree that PG is not always making the best choices and deputizations in his struggle to maintain the quality of the community. I understand that both decisions to pursue openness and exclusion in a large community will drive away some quality members, but the exclusionary tactics (banning the wrong kind of people) upset people philosophically opposed to it in addition to causing the atrophy found in exclusionary policies as I said earlier.
I hope that you'll stick around and contribute some great content, but if you don't, please influence TheList or whichever community you prefer to embody that anti-totalitarian hacker mindset and thus to really compete with HN. We will all benefit from that.
But, not everybody can make a website that succeeds at doing one of the things Hacker News does better than Hacker News, and I stand by my saying that an open community founded by elite people will be more successful and less elitist than an exclusive community founded by perfectly good, but not elite, people. And this is relevant because one of your core aims is avoiding community dilution/decay with your karma system and exclusion (the invite system.) I would not bring it up if it was incidental.
I, sincerely, would really like you to prove me wrong, though!