This is where the topic editing feature comes into play; any user can change the topic of a message sent recently, and if someone posts something in a wrong topic, it can be moved to a different topic.

Also, after a while this paradigm grows on you and by forcing you to think of a relevant title for your conversation, it forces you to have more cohesive conversations in my view.

And, lastly, it is possible to send messages without any topic (it defaults to (no topic)). :)

I’ve been wondering about this. Instead of topics, why not use hashtags? I know in Slack the hashtags indicate the channel, but they don’t need to. So instead of having set topics, you could just add a tag to messages to indicate the topic.

When a user is forced to make a decision on something like ‘topic’ just to send a quick message, you’re more likely to get randomly assigned, meaningless topics. Random hashtags, on the other hand, are no big deal. Because you have to actively search for the ones you want.

This has been the paradigm since Web 2.0 and it seems to have worked pretty well.

Random topics are no big deal in Zulip either. You can either a) edit the name of the topic at any time if needed or b) create a new topic as topics are cheap

Slack channels (and Zulip streams and HipChat rooms) are not "hashtags", they're IRC channels in modern form.

When a user is forced to add a tag for a message, you're more likely not to get anything tagged and therefore decrease the utility of search.

So you're going to start auto-assigning a tag, maybe based on their last message, which brings you back to channels / topics / chatrooms.

That's the approach that we take in Braid chat: https://github.com/braid hat/braid

Works well, although some people are put off by the similarity to Twitter #sigh