High plat matchmaking

Was in plat 4 around 2 weeks ago, climbed all the way up to p1, and i have to say that has to be the worst area i have ever tried to climb through period. Riot, if im plat 2- plat 1 it means im trying to get diamond 5. You matching me with diamond 5 players is fine if im plat 1 high lp. But the problem is diamond 5 players i run into dont care if they win or lose generally. They are already diamond and they just lock in whatever the hell they feel like playing that day. They think since they are diamond they can play whatever and do perfectly fine. Why should I have to play with people who dont give their 100% when im giving mine?