[neuralk]

The article is paywalled, unless you have access through a university or other library.

The high price you'd pay for paywalled papers goes in large part to the publisher for no real tangible benefit. Most research, and likely the linked article, are funded either directly or indirectly through public funds like taxes. So it is especially obnoxious to see an interesting article like the one linked be locked down.

As for why it's bad etiquette on the front page of HN, the free-and-open ethos common among hackers (at least, old school ones...) would usually see someone link directly to a pdf, instead of this.