You don't have to click into topics. Zulip has a "channel view" which lets you see all messages in a channel, chronologically, just like Slack or Discord or IRC

You don't have to click into topics. Zulip has a "channel view" which lets you see all messages in a channel, chronologically, just like Slack or Discord or IRC. That's actually the default experience when you click on a channel in the sidebar. It also has an "entire server" view if you want to see everything in one stream.