So the point is that they can start their own threads and reply to threads they have started, but they can't reply to threads that other people have started?
Wouldn't they simply then go and start their own threads in competition with existing threads just so they can post in them?
What happens if you merge a thread they started into another existing thread so that they are no longer considered the thread starter?
Just trying to think through the ramifications of doing this rather than simply limiting their ability to post at all.
I find that thread bans are a very effective tool for managing problem users - if they continually take a thread off topic or cause problems in that thread, simply ban them from posting in it. Achieves largely the same effect that you've suggested without arbitrarily limiting them to not being able to contribute to other threads.
From my experience, most of our troublemakers largely only cause trouble in certain topics (eg politics, religion, or perhaps a specific thread about a topic they are overly passionate about or like to troll in), and so a more targeted approach to managing them via thread bans works quite effectively.
If they are causing problems across a wide number of threads such that you can no longer trust them at all to post in threads other people have started - I think you've likely got to the point where they need to be banned outright?
Perhaps the dynamics on your site are significantly different in a way I don't appreciate?
Just thinking out loud!
