https://techcrunch.com/2018/07/18/reddit-chat-rooms/

If you’d rather spend time chatting with strangers who share a hyper-specific interest rather than keeping up with your coworkers’ stale memes on Slack, Reddit is ready for you. The platform has quietly been working on a chat room feature for months now and today it expands beyond its early days as a very limited closed beta.

Plenty of subreddits already make use of a chat room feature, but these live outside of Reddit, usually on Slack or Discord. Given that, it makes sense for Reddit to lure those users back into the engaging on Reddit itself by offering its own chat feature.