It's also important to remember that social norms are not consistent across the entire world. Some cultures are more deferential and others are more confrontational. On the Internet you are never sure exactly who the audience is, and in fact the audience is probably mixed. What seems like stern but helpful advice to one user comes across as browbeating to another. Very polite (deferential) people may not convey the seriousness of a situation to someone more used to direct speaking. Even inside of cultures there can be quite a lot of variety depending on factors like social standing, gender, and cultural identity.
This is why it is useful to talk about manners and customs even though it seems like child's play.
This is why it is useful to talk about manners and customs even though it seems like child's play.