Why isn't there ranked teams?

I understand that there is ranked flex and you can have your own team of 5 in it, but I feel like it'd be so cool to rank up with a SET team of 5 where you have to put in the system who your team of 5 is so you have to have the same players to be able to rank up or start a new team or something like that, i mean if I had 4 other friends over or something like that I'd love to be able to queue up and beat another team who is communicating just like you are to win. Any thoughts?