There are two kinds of people you can meet in VR: Friends and strangers. Friends, you can meet privately. You don't need a public space 'verse for that. And as for jostling around or randomly talking to strangers, well, you can walk outside or go to a bar.
It seems pretty nuts that Facebook would actually put its chips on this proposition. I can only view it as a totally desperate attempt to distract from the train wreck of their core business model.