Major news outlets carry a small ranking penalty on HN (it's in the software), since loads of uninteresting articles from major news outlets are constantly submitted.

The URL can always be changed if there's a better source. Just email them.

Major outlets get skipped for pay wall shenanigans. Known sources essentially aren’t worth clicking on, since you can’t read them anyways.

This is an internet culture problem in general. People have decided they can't trust the "mainstream media", possibly for valid reasons, and then fall face-first into trusting all sorts of completely random sites. Your other comment is very correct.

I think it's mostly because editorializing titles is not allowed. So to emphasize the part you deem most important in a story, you have to find an article that uses it as the title.

I've also wondered this - but I assumed it was more because most people post on HN after seeing it elsewhere. As the more 'strange' outlets (often) favour clickbait titles they get more shares/go viral more often (because people love to share without reading the full article). So I figure there's a greater chance someone will see the stranger version on social media over the (perhaps) stuffier/dryer version with the decent reporting from a more credible and less clickbaity outlet.

As an aside, HN is usually pretty good about switching the link for something better when prompted.

I wonder whether it is more a timing issue. Mainstream sites are submitted first, but overlooked. Subsequent submissions have to use other sites and those are the ones which finally gain traction.