There really need to be punishment for playing poorly, especially at higher ratings

I'm semi-consistently getting teams of Diamond players who have absolutely nothing beyond mechanical skill.

I just had a game where my team was 2-17 at 16 minutes. Bottom died 8 times, mid died 4 times, top died 4 times, and I died once in a counter-gank. All four players were playing immobile champions and permanently pushed to the enemy tower. I pointed out that they need to stop pushing, because I can't cover counter-ganks in all three lanes at once, and they just ignored me. Top and middle didn't even use their trinket wards consistently, let alone buy any wards.

This really isn't acceptable. I expect a certain level of skill and knowledge from anyone who can reach Diamond, and I'm not getting it. These aren't players on tilt, these are explicitly bad players, and I've been encountering more and more over the past two seasons.

What is being done about this? Is it supposed to be okay that this many players are completely lacking in literally everything but mechanical skill?