Do you need to try and keep pace with Facebook’s functionality to retain your members?
Some features have become standard in most platforms (@mentions, a wall of updates etc..).
But you would struggle to name many.
Most members in most communities aren’t asking for more photos, private messaging, disappearing videos, and a wall of personal updates.
Don’t try to compete (or keep up with) the world’s biggest company with the world’s best developers. You will just be seen as a ‘worse Facebook’.
Compete where Facebook can’t go. Have unique customisations for your members, create community-specific member journeys, name parts of the community after key terms, proudly display your shared history, build a stronger, smaller, tighter community.
Members don’t expect you to be Facebook, they expect you to be the best place in your field to support their goals.