As someone whose moderating experience was unpaid, I can tell you part of the reason for that: We resent having to deal with assholes who make our jobs difficult and don't appreciate us giving our time and energy to the site for free, because we believe in the cause.
No, it is not a neutral forum. There is no such thing.
Also, my honest feeling is "Feel free to start one." That isn't snark, but I assume it would be interpreted as such because you are asking people to start this rather than saying "Hey, guys, I am tired of this and I have started an open source version over at (THIS LINK) and if you are as fed up with HN as I am, hey, here is an alternative."
People who propose the kind of seemingly idealistic suggestions of the sort you are proposing almost never want to roll up their sleeves and do the work -- because, hey, work is hard and no one is paying them and yadda. Which is likely why HN is the place to be for so many people: Because it is well moderated by folks who get paid, because it supports a business agenda and doesn't need ads or the like to pay the bills. The business -- YC -- is plenty successful and can afford to support the forum for its purposes in a way that doesn't unduly impinge on what people can discuss here.