Why couldn't dynamic queue just replace ranked 5s?

If dynamic queue was built like teambuilder, meaning that you found a team before a match, it would have worked with solo queue. It could have been sold as a way to make ranked 5's more easily accessible to everyone who wants a more "team oriented" experience. It would have been fair and people probably wouldve enjoyed it, but now we're stuck with this system forcing solos and premades to play together when most of them just don't want to.