RIOT why? Matchmaking Silver to Platinum (normals)

I have had 2 (normal) games in the last week that matched silver vs platinum. The first about a week ago was me (silver) vs a plat -- a face stomp. My last game, my poor teammate was mid against a plat. Guess what? The plat stomped the entire team because they snowballed so hard off their mismatched lane.

I know that normals have a different rating than ranked. But this is NOT a fair or fun match when this happens. The game was basically ruined for 9 people. Five on my side getting our faces stomped, and 4 very bored people on the enemy team who might as well have gone afk cause the plat took almost every kill.

Perhaps normal matchmaking needs to use ranked mmr when considering a normal game. I'm sure their ranked mmr is a more accurate measure of the player’s skill.