You can already make steam friend group chats, it was just a bit janky when I last used it like 5 years ago

I primarily use Discord but also have a long-running Steam group chat.

Steam group chats are still janky and by no means a Discord replacement. It feels like an MVP that they lost interest in shortly after adding the feature.

It's fine for a couple people with no real need for moderation but beyond that I don't think it's currently viable.