Sometimes people can be ridiculous. What fans of groups that attack other groups should understand is that every idol is human. They all get hurt, just like we do. It makes me angry to hear of anything like this in any fandom. Knowing that Hyomin didn't mean to offend anyone, of course it becomes even more aggravating. Especially since she even publicly apologized. Have the fans never joked around with other people? A lot of fans need to learn to have a sense of empathy.
Honestly, it's outrageous how bad things can get sometimes over something so minor. Even with Korea's deep seeded system of respect and politeness, this incident isn't something so bad that you would constantly attack an idol for. Or rather, attacking an idol is never necessary.
I hope Hyomin can stay strong. Even for the strongest person, these things do get to you every so often regardless of that. Sigh.