They can't have their own account until they're 13 but they're allowed on the platform. I think Meta is making the VR experience worse for everyone but greed is steering that boat.
I mean really is it gonna make a difference? I hear so many kids on Pavlov Shack for example that are easily under 13, so much so it's made me setup a seperate Window$ install just to play the PC version. I don't even see the point for an age barrier anymore, aside from legal reasons if those exist.
Don't settle for the, "Well there should be an age requirement to keep the kids safe online" crap either. Keeping a kid safe online is a parent's duty, not a profit-driven megacorporation, can't oversee what your kid does in the game? Don't give them the bloody game then.
I sometimes wonder what the parents are actually doing though, I had a run in recently in Pavshack (PC was unavailable, blender render) where this kid was just screaming down the microphone all sorts of profanities and slurs. That mic peaked more than the himalayas.