In the old chat, people mostly just chatted and talked about general topics, not just about heroes.
And no one forces anyone to reread the chat history. Maybe it will be cleaned once a week, like before.
Almost no one rereads the chat history, but it may contain important information, for example, a discussion of cool moves in a game among 10 players, which would be unavailable to others. If this discussion started on the forum, it would be saved in a thread forever, and everyone would see it. This is what makes the forum's content unique and thematic.
So, a chat for casual chatting is a bad goal in itself.
It is necessary to create a forum chat – a multi-room chat for thematic conversations. We all know what casual chatting is – it's a violation in the end.