I am platinum. Like everyone knows I wont be able to queue with silver players, fair enough.
The reason for this is obviously the skill level might be too big. Very obvious, right?
Then why can I get matched with with a gold 1/2 player who duo's with his silver 3 friend?
If you duo with someone your MMR becomes higher than it normally is because of teamplay advantage. I guess because of this they somehow get platinum matchmaking. And in this case they were playing against a full team of platinum, gold 1 players, with no silver players themselves.
I think this is really unfair for the other players of the team with the ''bad duo player'' inside and totally counters the whole purpose of not being able to queue with 2 leagues lower than you.