If you’re in a topic you don’t need to reload - new posts show up. You only need to click/reload when you’re browsing a topic list - new topics float to the top. Could you imagine the UI nightmare of being on a site with topics moving around all the time? 
That’s great! It means that people (in theory) take more time to consider what they are writing and how to structure it so that it will be usable in the long-term.
Chat is for right now. We (Discourse the company (CDCK)) also use chat but treat it as ephemeral and discardable (we actively purge chat logs older than X days - if it’s meant to be long-term it goes into Discourse).