Not sure about Roam, I've been using Obsidian, and my purpose is for personal, making note archive offline. So never had any need for collaboration. But with Sync and Publish features, maybe there is a possibility.
I think Roam has been fully collaborative since the launch. The browser keeps the whole database in IndexedDB and syncs it continuously with a WebSocket streaming Datomic-style transactions.
I'm most saddened by the people who spend their time writing plugins for Notion / Roam (and to a lesser degree, Obsidian), providing extra value for free to a non-free product that will profit off the free labor. (or rather, I'm saddened that companies like Roam are so willing to exploit community engagement for a profit)
Time would be better spent contributing to an open source alternative like Athens!