Facebook also has the data. They see at first glance any uptake of a new social network of any kind. They automatically prevent sending invite-links or even just invite text messages via FB posts, FB chat, WhatsApp. So if you try to reach all your friends and try to invite them, you can assume only a few will even see the post in their newsfeed, get the chat post - it's like shadow banning posts. They create a filter bubble for you.