Great idea! We have been working on the nuances of this, because it's definitely a feature unlike any other and something I personally believe will be very important to allow users to remove themselves from any confrontation without it causing a problem for others.
We employ a feature on some of our other projects that lets a user enable a permanent status on their account that will squelch any interaction of another user, and prevent them from privately interacting with them either. We intend to use a similar function that will prevent anyone from being harassed by another, and all without having to wait for a moderator to get involved.
This feature is not currently enabled, due to the complexity that is needed, but I will bump this request for you.
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