It's that fucking readyplayerone movie. They all saw that and thought "what if everyone was obsessed with a virtual world, and there was only one virtual world that was basically a monopoly, and what if we controlled it all" without realizing how dumb that is and that competing, and likely better software will definitely end up being created organically by people who care about the end result more than they do about money.
Exactly it needs to be an open standard or there's no point. Someone pointed out the other day that Epic has a much better chance of creating a metaverse by leveraging fortnite user created content. Still isn't ideal, but it's better than anything Facebook is offering, and at least has something that a future standard to build on.