Flex queue wouldn't strictly require solo players if 4-man premades were disallowed

Two pairs/trios of solo players would still be able to enter Flex queue per match if matchmaking could only find a two trio/pair premades, respectively. This would require that Solo/Duo queue just became Solo Queue, since duos would just want to enter soloQ instead because of the (perceived?) advantage it gives them over solo players.

needed match types: 5 v 5 3+2 v 3+2

optional if it reduces queue times or if solo players enter the queue: 3+1+1 v 3+1+1 2+1+1+1 v 2+1+1+1 1+1+1+1+1 v 1+1+1+1+1