For me IRC scores points on not having push notifications, rich text, custom emojis, embedded images/video, etc. It’s plain text communication — multiplayer notepad, if you will — and it’s great at what it does. I love that I don’t need anything but a terminal window for utilizing the full capabilities of IRC, and the lack of persistent chat history is a great counter to FOMO. (Yeah, you can stay online or have a bot that logs everything — the point is that most people don’t.)