What do you see as the gotchas with Zulip for community use? Zulip is 100% open-source, and we sponsor our hosted services (mobile notifications, etc.) free for OSS projects.
But Zulip’s default view is a list of all messages in all threads in all channels which has no context for the individual messages, like
The combined feed is helpful for some (e.g., in lower-traffic organizations, or if you like to see messages as they come in), and was the default home view many years ago.