online fandom behavior doesn't bother much but in person behavior is really important as it can cause anything between inconvenience to dangerous situations.
For example I saw some vids of other fandoms pushing each other in merch line of Tokyo dome. That could get really dangerous and it might cause stampede. Luckily when I went there, shawols were very calm.
On the other hand when I went to Amber's fan meeting I regretted it so much. She got the most trollish obnoxious batch of fans. They were howling and yelling the whole time. Kicked my chair at the back. They even freaking yelled at her while she was talking. I don't think I will ever go to Amber concert or fan meeting again. Terrible experience