I think they chose 16 because some of their biggest stars are in the 16 to 18 age range (for better or for worse). For example Charli D'amelio, who has 100 mill

I think they chose 16 because some of their biggest stars are in the 16 to 18 age range (for better or for worse). For example Charli D'amelio, who has 100 million+ followers and has become a celebrity in her own right. I personally agree that it should be 18, and ditto for Instagram and YouTube etc, but I expect that is the business reasoning behind the decision.