Silver gets matched with Platinum in ranked

I saw similar thing more than once and i dont quite understand WHY. You wont even be able to invite your silver friend to play ranked with you if u are plat, yet you can get silver on your team completely free of charge without even asking for it. And it ALWAYS goes the same way. If there is someone from MUCH lower division in the game, he ALWAYS ruins it. He simply does not belong. Im pretty sure low plat would be useless in the similar way if he was matched with master tier players or something around that. Thats why we have QUEUE LIMITATIONS right? Which basically - u can queue with people one tier above and one tier below yours. So why the fuck there are people 2 tiers below running around? Sometimes you can see both teams have someone really out of place (not by my observations but simply by their division and tier). But most of the time when this happens. its just one person completely out of his league. Am i missing something? Im completely fine with any uneven and disbalanced teams in normals. But in ranked i kind of expected to see something at least not going against common sense.

Im just curious. Is it some kind of a bug? Or Is this how system supposed to work? Nothing out of ordinary? Then what the logic behind this? You cant invite your own personal silver with whom you at least will be able to communicate but you will be gifted with silver that might not even speak your language or possibly ANY HUMAN language at all.