Is the matchmaking system supposed to be like this?

The whole day in ranked, I've been getting silvers on my team and plats on the other team. I am gold 3. This last game I got a silver 3 graves that I had to support and we faced a plat 5 cait. No, the graves wasnt godly, he ended the game with 98 cs while cait has 214 and he also did not know how to lane against a cait as he would walk into the and die to get 1 cs. (He picked graves into a cait.) I dont see how this is fair. An 8 division difference seems way unfair.