I disagree, no offence <3. Whether it's fluffy vanilla or dark and morally questionable, the way the story is told, the way the author develops the characters and emotions, and the way the subject matter is handled are important. These things go a long way towards deciding whether a manga is enjoyable, or at least well executed. That's the kind of thing people have been criticising in the comments, from what I can see. There's a big difference between hateful comments and legitimate criticism.
I understand that you feel some comments, esp. with strong language, are insulting the manga. But I think comments like "irritating" are still legitimate, because I felt that people found the way the plot and characters developed irritating. I think they're justified in saying it. All kinds of art and literature are created so that people will react to it, and the comments are people's reactions.
I do agree that it's always better if people explain WHY they find a manga shit hole - but the person below did that!!
Hmm I dont think this one is that bad. Surely the little brother did bad things, which would not be considered acceptable in reality. But here in a fictional work, I guess paying attention to the emotional aspect