Facebook is still being used, the majority of users are between 18 to 44 as can be seen on statista thru google search. However there is basically no young people. Having this dating feature kind of matches with their adult demographic who likely can pay. After all fb is dying with no young people signing up in North America, its gotta find a way out. Note that around the world but not North America and Europe there are still many young people signing up for FB.