I mean. Can we implement a thing that looks like FB and has all the right features? Sure! Everyone currently on Mastodon will love it and flock to it.
And everyone else, that is most of the real-life people out there, will stay on FB. And we'll stay too because otherwise we won't see their photos and won't get invited to their events. Because everyone else is there, and because you don't know That Guy From Work's handle so you can't actually send him the invite on not!FB.