Why not? Simple: I don't trust Meta. And what I mean by that is, that I do actively distrust them in the sense of: if they made it, it must be bad for me and I should not use it. It is a little bit like if Malboro tried to sell you vitamin pills all of the sudden. Maybe they are good genuine vitamin pills, who knows, but I would not be the person to try that out. And even if there was conclusive proof they were good genuine vitamin pills, I would like to give my money to someone else.
Facebook would be a decent product in the hands of people who knew how to wield it and how to earn (and keep) a users trust. Similar any VR they develop could be technologically really a masterpiece, it would howver still be a masterpiece managed by Meta.