I don't see what are the significant barriers? You can still comment, post new links and articles and read like anyone else. If whatever you say has merit, then nobody will care what your score is in the hacker news game.
If you run HN with "showdead" you'll see the cruft that gets killed. This stuff actually really represents a real danger to every online community.
Point is, there are real people who edit HN, and these people use karma score as a major determining factor when deciding whether or not to mark as dead.
This is aside from the typical flame or personal insult... that anyone can and will do, even those with high karma scores. ;-)
"... I don't see what are the significant barriers? ... If whatever you say has merit, then nobody will care what your score is in the hacker news game ..."
I think rantfoil is saying it is easy to get "tripped-up" on the unwritten or obscure rules. I guess the "Turing-like" test to participation is understanding how "hackers" think.
To me "Mending Wall" is more about people's inclination to be open or closed minded. The comfort the narrator may gain from leaving the wall open in places comes at the expense of the neighbor's preference for enforced separation.
Unfortunately I don't really understand what point the author of the article was trying to make.
And note that the vast majority of sites requiring any sort of identity are pseudonymous.
If I make an offensive comment on HN or reddit, my exposure is limited to downmods. A site which requires a real name and affiliation exposes me to considerably higher risk.
EDIT: you're right, of course, it depends on the flame. Perhaps I should say I haven't seen a lot of online crap that ranks ranker than a dump on my porch.
We have to use a spell to make them balance:
'Stay where you are until our backs are turned!'
...
It comes to little more:
There where it is we do not need the wall [...]
...
[...] Before I built a wall I'd ask to know
What I was walling in or walling out,
And to whom I was like to give offence.