I dunno about you, but I and basically everyone in my circles at the time agreed that it was most likely a terrible idea.
Until and unless there's a truly convenient piece of hardware to get one into a virtual space—I'm talking weight and bulk comparable to prescription eyeglasses, no wires going beyond your body (ie, maybe a pack at the belt/pocket/something like that), and some form of extremely intuitive UI—you're not going to get people interested in regular interactions in a VR/AR space.
Frankly, even once we do have something like that, I think it unlikely that many people would choose to do things like meetings in a virtual space over something simpler like Zoom, even if they did already own the hardware.
And none of these views have changed over the past few years.
No; I think Zuck has been far too isolated and out of touch with how regular people operate for too long, and when faced with, as you say, the fact that Facebook was only running on other people's platforms—and it became clear that no one was interested in making Facebook their platform, like by buying a Facebook phone—he convinced himself that this was The Next Big Thing based on sheer desperation.