I'm not sure I agree with this. Firstly, I don't see how making it impossible for someone to post in a thread makes the conversation flow, especially if they then start their own thread and you get two threads going.
Secondly, if people are reporting actual trolls, the mods will be banning them...
Also, what about the people who are on the ignore list of those who start official match threads, or ratings threads, or big news stories. We get enough repeat threads as it is, do we want to install a system that will force people to have to start new threads to comment on a topic that already...
I wouldn't be a fan. The people on my ignore lists are the people I don't want to read. But they get responses elsewhere, so some people must like what they have to say, so even if I'm not interested on what they have to say on a topic I bring up, I would imagine others might.