The ignore button proved useful at alien-ufos.com because they are a rabid bunch of liberal idiots--some with pathological hostility toward Christians and conservatives.
Have virtually never felt the need here except maybe the first year or 2.
There was some kind of 'free-for-all' on occasion that could be quite hostile.
FR is relatively quite tame, now, imho.
However the recent thread hijacking on FR by the anti-immigration crowd has made me want for an ignore button at this site.