>>512213079 (OP)
Instagram is their way of screening you. They need to know how popular you are and they need to get you approved with their girlfriends (for which being popular and having high engagement is a prerequisite). If you don't have instagram, it will give them the ick. When I was a naive retard (and probably still am), I was on tinder and a girl asked for my instagram, when I said I don't have instagram, she blocked me.