In an ideal world yes. But from past experience many users have the association for mailto links misconfigured.

It's a terrible user experience.

Yes, it depends on the target audience. For a personal website which the article was about, it would probably be fine for most hacker news users. If someone can’t manage to send me a mail, they probably wouldn’t see my website anyways. If you do your grandparents personal website, a proper form with a backend is better though.