@young_speccy
If there's no warning, that's fucked, not everyone can stomache to see that shit. However, if there is a warning (Like here) it gives anyone who is very uncomfortable with it to skip the chapter.
Just like how there are ratings for films and games to tell potential users its contents so that people who don't like it to not buy it, the same applies here. The author is trying to tell a story, and they can do whatever they want to convey it, even if YOU find it gross.
And to be honest, don't even try to be on a high horse here. What about people who have had their loved ones taken away because of manslaughter or murder? People who have lost their friends to freak accidents with animals? You also going to speak up for them as well? The second this manga portrayed killing and being killed, its already telling a story with elements that will make anyone uncomfortable to some point.