There aren't enough players in order to have a queue for premade vs. premade. If they were to implement it they would need to limit the hours in which the queue is available or else people will just play during odd hours and do win-trading like GordonGeeko said. I think they also said in the latest Live Letter that they will do adjustments to matchmaking so queue synching will be harder to do. (Queue synching = queue at the same time so you have a higher chance being on the same team.).

They did have one season of The Feast where only premade teams were allowed. It died pretty quickly. Very few people bothered with it.

If you really want to play CC with your friends, the best you can hope for is that the upcoming official European Cup is a success, and they do more tournaments in the future. There are also several discords that do unofficial tournaments all the time.