We set a limit here to mitigate potential abuse — users who might start large group chats to spam community members in a way that moderators would have more difficulty identifying / controlling.
Is this limit causing problems in your community?
We don’t have a specific plan on our roadmap around adding threading in group chats, but I can see how it would be helpful, especially in group chats with lots of members. I’m happy to add a feature request for that functionality so we can keep it in mind for future development.