I think it's basic manners that when someone writes a long piece about a subject they're struggling with, you shouldn't just respond that it's "stuff people should have learned by the time they turned 12 years of age".
It's basic manners, but we all struggle with basic manners sometimes, especially on the Internet.
The basic manners that you learned early on for interacting with people face-to-face don't scale to interacting with many many people in an issue tracker every day, anonymously, asynchronously, over the internet. It's a weird circumstance that we didn't evolve to handle, so I think it makes sense to break it down and carefully look at how to handle these situations efficiently and positively.
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.
It is kind of sad that so much "social" advice on the internet consists of stuff people should have learned by the time they turned 12 years of age.
In any case, I am glad the OP is making an effort in favor of gentility.