When we think of such tools we tend to think it would be US using them, not THEM. But that is unrealistic.

Just because any such implementation would give the same tool to trolls, no way to avoid it. Diaries would be smited right and left, for retaliation, even. If the admins would like to see a site completely out of control, implementing a button like that would probably do it.

Hillary supporters would be motivated to 'smite' Obama diaries, the most well written ones most of all, Obama supporters would want to smite HRC diaries similarly ... and that doesn't even get to the true trolls, who just want to destroy dKos and Progressivism. The best of the non-candidate rec list diaries would be their first priority for smitism. If they got them before they ever got to the rec list, when not many smites would be required, what would be left to read? Heck, they could smite all diaries fresh out of the box, and instead of 200 - 500 diaries a day, we might get 30. If that. How much incredible writing might be lost in the time it took to correct the policy?