Posts to pages behind impenetrable paywalls get flagged into oblivion.
Why does it happen so often here when anyone submitting can easily find a non-paywalled source with the same information?
Because this usually isn't the case at all. Quality of sources varies considerably, and HN always wants the best one.
And they complain about paywalls.
And they complain about subpar journalism.
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HN may just have a different proportion of complaints.
As to why you see it here, it probably has to do with the topics that this site likes. Business, for better or worse, gets a fair bit of air time here. That's one area that has typically charged for access to its news/research.
Secondly, I'd argue that there is an element of "you get what you pay for". I pay alot more than the average person for access to news, and I strongly believe that this is true.
Thirdly, many of us make our living by having others directly pay for what we produce. This can make you a bit more sympathetic to the idea of paying for the work of others.
"You get what you pay for" is mostly a marketing effect, not an actual phenomenon.
Perhaps you are right, but convince me. What research are you basing this on?
If you're not careful it's much easier to not get what you've paid for than to get more than you've paid for.
Because this forum values well-thought-out articles. These articles generally require a lot of time to compose. If the authors' don't have some other job, then they have to be paid for their time. In order for the company to acquire the money to pay, they need to collect money from: 1) advertisements, which for general-audience text media, aren't that valuable.
2) subscriptions, which few people will pay for if they can get the content for free.
Too bad it often 'breaks' the internet as we know.
Also see this comment by ljsocal in this thread.