reinforcing negative behavior
It's pretty simple, you give a player who is disheartened by the players they received in solo que (e.g. - 4 marksmans and top main, one of the marksman takes top and all of them feed while you are stuck supporting) a "punishment" for sitting in fountain instead of continuing to feed the massive fed enemy team. The punishment is this: you get a pre-que timer of 5:30 ++++ minutes and blatantly tell them "you are in a lower que priority" - (AKA. - get ready to play with people -200 of your MMR).
How does placing someone in a "lower priority que" not reinforce the frustration that it takes one to be willing to AFK?