First they will add loads of new users and become the dominant instances. Then, they will add their own proprietary features that other instances cannot support. Finally, their extensions become the new de-facto standard, marginalizing the original implementations.
Since Meta has proven itself to be an evil company that does not act in good faith, it is better to not federate with them from the start.
Basically this: https://en.wikipedia.org/wiki/Embrace,_extend,_and_extinguish
First they will add loads of new users and become the dominant instances. Then, they will add their own proprietary features that other instances cannot support. Finally, their extensions become the new de-facto standard, marginalizing the original implementations.
Since Meta has proven itself to be an evil company that does not act in good faith, it is better to not federate with them from the start.