Most often it turned out the complaining person was the problem.
Worst cases were third parties who requested such actions on behalf of the "victim". They were loud, asked other members to complain too and even showed up in our offices to demand account closings - without any proof or valid reasoning.
I never understood how people handle their real lives without being able to argue or verbally discuss such issues. Even if these include occasional insults. IMHO these are just words - you don't need to cry for higher authorities (site admins, conference organizers or law authorities) all the time.