I think FB and a lot of VCs are going to learn that virtual worlds are boring, if not awful, unless they're tied to an addictive game loop. It'll be six years since the Vive came out, possibly the first "realistic," open-ish, mm tracking, high performance, modern VR set and there's still no killer app for VR. Worse, the VR market has decided its all nonsense anyway and is fine with buying headsets that just run mobile phone chipsets because that performance and graphics is "good enough" and no one is demanding a photo realistic world to lose yourself in. All they care if the games are good enough, that is to say if the loop addictive.
Those pushing out past games in VR are brave and I'm thankful they are there. Maybe Meta will figure it out, but I'm skeptical.
Even a decade before I was “playing” Worlds, Active Worlds, and 3D Anarchy. Those were just 3D chatrooms like SL. The charm had already worn by the late 90s though.