I just found this cool utility a couple days ago and have found that it’s a great solution to sandboxed versions of Discord being unable to provide rich presence. It’s a Python script that queries the Steam web API to get info to forward to Discord’s API. The “installer” sets up a systemd service that will auto-run the script for you.
It requires you to get your own Steam API key which was a trivial, though slightly buggy, process for me. You can optionally use your own Discord app ID, or just use the one owned by the guy that created this script.
For many people, socialization is a core part of gaming, and Discord is far and away the most common platform for that socialization.
Steam has chat
It’s not a matter of what people can use, but what people do use. Like it or not, Discord is the de facto standard, and it’s a lot easier to install workarounds that make Discord usable on Linux than it is to convince all your friends to switch platforms.