With the same token that you say HN is not a CraigsList, when an HN-responder puts an effort in going through their product and writing a personal note inquiring about a possible opportunity at their company, posters should have the courtesy to respond to the responder acknowledging that in-spite of their good/bad profile they can't hire him/her.
I know these two advices are from me to you and you to me. All the remaining folks who have been one-liners will continue to be so.
Btw, I am a graduating student from IIT Delhi, who have applied to many startups that interested me with a personal-note and list of projects I have done with clickable-links. While about 10% of posters responded saying that they did like my profile but can't take it further because of visa, remaining 90% never responded.
While I am not the best engineer, when my detailed & clear personal application doesn't get an acknowledgement reply, I can imagine why responders are just sending one-liners. If posters want to hire, they will hire from one-liners. No point of detailed-personal application.
On a side note, my profile with links to projects is https://gist.github.com/sravfeyn/13534c67812183235a2c/ I am hunting for an engineering position at a start-up with product-innovation.