I worked at a place that used one.
Because the actually functionality they provide is the same as Slack, but worse in basically every way, is maybe why.
If you just lift over what you have in 2D it becomes only more painful. But this is what most people do. Also many platforms, like Microsoft Mesh. Yes, it's cool that you can join a teams meeting in VR. But until they add something that actually takes advantage of being in VR, all it does is add more friction. Roasting marshmallows and other cutesy minigames does not add any value whatsoever.
And I expect even a VR meeting space would see more use that’s worse than a normal video call but is happening because someone in charge is over the moon for it, than it’d see use in the far rarer cases where it’s really better.
Teams has breakout rooms but they are very rigid. You have to switch to one and define them. You can't 'glance over' and see what the other rooms are doing. It's much more flexible to just walk around in a 3D space, work on a shared whiteboard you are standing around, pull in some powerpoints to discuss, and walk over to another group if you're needed (you could see them wave over). At this point it really becomes a real alternative to flying over for a workshop. Thus saving many tonnes of CO2, and much cost in flights and hotels. VR is not quite as good but it's much better at dynamic workshops than a simple video tool like Teams is. Added bonus if you are discussing potential upcoming products that you already have 3D models of. Just picking up a model and going like "Hey why don't we put the USB port on this side", this is really where this shines.
But the tool has to be really good. Other solutions like Arthur, Viverse and Spatial could do it really well (Spatial has since gone full consumer-oriented though and has lost many capabilities for business, it's now more of a luxury VRChat). Mesh can not, it is extremely limited. It's the old AltSpaceVR but dumbed down. It would have been better if they kept AltSpace as it was without messing so much with it.