What do users really need from a platform beyond basic social features and the ability to, you know, launch the game?

I've used Steam chat and voice comms all of about 3 times. Discord is better.

Profile pages and achievements? Couldn't care less.

Streaming? There's Twitch for that.

What I really care about from a platform are the games that are available for it. Valve waved the white flag on that a while ago when they abandoned first party game development.