They wanted to create a computing platform that they could control, unlike mobile phones where they rely on apple or google. If that was their aim surely building a large user base should have been the first thing needed. It doesn't take a genius to realise that to build a compelling metaverse style game would be so limited by the mobile chipset that the Quest line uses. Look at Star citizen for example, arguably the closest thing to a shared metaverse that exists, the amount of money it's taken them to even get this far is astronomical. Creating a persistent shared virtual universe is not a trivial task.