I can see your logic, but as most people who don't ignore the user will quote the persons post anyway, there isn't much point.
People must learn to ignore the trolls/annoying posters - and if that user is really bad - then that user should be banned.
If your talking about a "digg" type style, I think that would mean a major overhaul of the system and I'm not sure that style is right for this forum.
"..just keep on trying 'till you run out of cake"