The "buy all your competitors strategy" couldn't work. After acquiring wahtsapp and Instagram and all the political games around Facebook there was too much regulatory, anti-cometition, ... attention on them for them to strike any serious deal.

While my impression regarding Metaverse was that Mark Zuckerberg was purposely imprecise on what exactly Metaverse was, hoping to find a company they can acquire, which then in a retcon made that exactly what the vision ever was.