Joining queue as Support-primary, getting mid.

How come when I join the queue as support primary and mid secondary, I sometimes still get mid? I know I shouldn't cry about getting my secondary role, but.. really? Last I heard there was a shortage on supports, so why wouldn't you allow the few people that actually like playing support(and put it as primary-role) actually play support?

It has only happened a few times, and luckily everytime it did happen someone was nice enough to trade(or someone remade it). But I just don't get it.. people are getting forced to play support while I get forced to play mid?

It is obviously a flaw in the system, I believe it only happens when someone leaves during championselect and the group gets remade, but srsly..

fix it ty