I'm an American. Before I read the article I thought of "informality" as an American value, which was indeed listed. If I read a preprint or blog post and contact the author I typically use the author's first name. I'd prefer to use a last name ("Mr. Smith" or "Ms. Smith"), and that's what I used to do, but people would reply to me with my first name, so I gave up.<p>I know that 30 years ago, South Koreans were more formal. Is that still the case? A South Korean postdoc at my university was uncomfortable calling his boss (and my advisor) "Richard". If someone is more comfortable saying "Dr. Smith", let them.<p>In general I would like to be more formal when corresponding with strangers, but that is unfashionable in the U.S. I am fine with calling colleagues at work by their first names. My children don't address me by first name, and I never do so with my parents.