I have intimate knowledge for many years about board feuds, disruptions, trolls and members who always refuse to ignore one another. Having the ability to block people that ruin your threads is awesome. I've seen endless times where a member would follow around another member like a lost puppy dog, and would then crap in every thread the other started. Having the ability for the member side to prevent this is priceless. If someone gets blocked by an "enemy", then I can't understand much why they would care, unless they are upset that they can't get their words in and feel like the other person beat them by blocking them. Truth is, there are more than enough other threads to post in, but being butt hurt by being blocked is the reality.
Oh, and the ability for staff to place a member on another persons ignore list, when they refuse to and endless threads get ruined because of these one on one feuds. Always wanted that option and now I have it. I think that's another invaluable option. Some obviously will bitch, but having members ignore one another and giving them the ability to save threads - always better than having to ban members outright.