Dynamic queue chokes it's own queue times
I doubt I'm the only one in this boat, but...
I've mained mid for several seasons, and up until this season I usually supported secondary. If I couldn't mid I'd play just about whatever the team needed, but if mid was taken and nobody was stepping up to support, that was my first choice.
In dynamic queue, if I put "support" or "fill" as either of my two roles, I'll overwhelmingly get support. So I don't.
I can't imagine I'm the only one who does this.