I agree that this _is_ a security breach if there's a legal agreement (a contract or TOS), and in this case this is certainly not a question of ethics. But in

I agree that this _is_ a security breach if there's a legal agreement (a contract or TOS), and in this case this is certainly not a question of ethics. But in my case, this is happening with informal communities. And btw, in case of Slack and HipChat, the data isn't "on-site" to begin with: it's already on someone else's server :) Also I want to point out that there's reason why users want to have their own copy of the conversation history. Most admins don't care about preserving history, especially if this means any hassle. Slack, for example, keeps just 10K recent messages for free teams, and having full history requires paying for Slack. If they can't pay or won't pay, the users are out in the cold. What else can the poor sods do?