Sometimes the game makes you hate other people. Sportsmanship only goes so far and Riot seems to forget real human beings are sitting behind the screen. My egotistic support Zilean who didn't passive me up once and bombed my farm from level 5+ and him and my top laner denied me about 50-60cs as adc and I was starting to get really behind. I pinged omw and asked them to let me have it nicely but they didn't. So what's better here, to keep on taking the abuse and lose out late or show these "back off I'll carry" attitude sub-plat players the only way they'll actually listen? If I took it I wouldn't have the spirit to make sharp plays anyway, you can only take it in your stride so many times a week.
The sad and backwards thing is that these players don't get banned. They don't get punished except for player retaliation but the rules prohibit this.
A plat friend I know irl ignored me and took my farm and I inted and it actually shocked him a little, even though I'd asked nicely. It was like he'd realized I'm also a human being with feelings and that griefing someone else's game because they made a mistake just isn't worth it. When you have a bad attitude people's words don't mean anything to you. He doesn't do it anymore and we play better together now.