You missed the point. The point wasn't the nature of the tool itself. Anyone could join, and one could chat with anyone. It was used "by the people" and not curated by corps.
ICQ was not "curated" by a corporation; it was produced and operated by one from scratch.
The present-day, mainstream, proprietary chat systems are open to anyone to join and chat with anyone.
Most of whatever restrictions they have are necessitated by spam. Allowing new members to immediately post unlimited amounts of material into any chat room or any other member's inbox is a bad idea, even in an open-source, federated chat system.
