Hmm a comprehensive ignore feature used in this place will amount to:
Bitty and fragmented conversations
Individually led Orwellian style censorship
Rage ignoring
Ex-moderhater and chucklesquad side kick ignoring
Fundamentally, I can see it being the squeezed trigger to a forum on its knees with a bag over its head. Forums are about free speech, no matter how f*cking annoying, condescending, puerile, vengeful, blunt or just downright trolling its members are.
Rules are dem rules, if they're broken then suspend, ban or slap an infraction on the perpetrator. Don't give the masses a means to bury their head in the sand.