For a short moment in 1995, PSYC was under consideration as a messaging protocol for the virtual reality modeling language, but it wasn't really ready for the job yet.
Mark Pesce had a vision of standardizing how VRML servers would interoperate so that one could navigate from one world to the next and interact with other people in virtual reality.
A majority in the VRML community decided to leave interaction of 3D worlds out of the VRML standard, however, and have each application implement chat its own way.
That's how MMORPGs like Second Life are still looking at that problem, today. Back then, no messaging technology was ready for that job, anyway. And even today it still takes work to do.