Consider that Facebook's conclusions are why they don't have anything remotely as successful as TikTok, for engagement.
> in the best interest of the users?
I don't understand this. Is this some moral motive? TikTok is an independent for profit company that has a product with better engagement than any other in the world. Within that context, yes, it's in the best interest for the user, measured by engagement.
As I said, I don’t understand the question. To understand I would be to know what “best interest” means to you, and in what specific context?
https://www.statista.com/statistics/264810/number-of-monthly...
It wouldn't surprise me if the total number of real users, not counting bots and alt accounts, is probably ~1b or less.