The problem is that confidently wrong comments are posted to social media like HN and Reddit so frequently that you'd actually be wrong assuming sarcasm most of

The problem is that confidently wrong comments are posted to social media like HN and Reddit so frequently that you'd actually be wrong assuming sarcasm most of the time. So now you're just admonishing someone for trying to engage a comment instead of identifying the epic "anime run funny" humor. IMO the sanest policy is to just allow people to respond earnestly to posts even if it might be a joke.