Being a high plat player in this game is the most frustrating thing ever

When you are plat 1 or plat 2, and every game you're getting matched with and against D5s, it's incredibly frustrating. They never carry, sometimes they even die more than anyone else. It makes me SO salty seeing diamond players in my games knowing how hard I'm trying to get there, and they're already at d5 just not caring at all about anything. What is the purpose of a rank if it is effectively meaningless? Just to get that shiny diamond border, but still get matched with platinum players? D5 is like hell on earth because it encompasses like three whole divisions for some reason. I don't even know how to fix this, but it sucks.