It seems like once people realize they're communicating with other real-life human beings, they are much more civil. Couldn't we try to consider that ahead of time, and avoid the off-handed negativity in the first place? It would make HN (and nonverbal communication in general) much more productive and enjoyable.
If the two comments combined fully capture your viewpoint, why not say something along the lines of, "Your advice is good and the post is fairly well-written, but it sort of comes off as a product advertisement. You cite scientific evidence, but you don't provide any sources, which makes it seem unsubstantiated."
Just a suggestion.