Why can allied champions troll you?
Gonna be honest, kinda tilted rn because in my last game we had a Trundle jungle who got pretty fed, but only ever came bot when there was a wave to tax. No, he didn't gank, he just came to tax. So I took his Krugs, which he didn't like. After that he kept using his pillar to cancel my recall. And obviously it's my fault because I trolled him when he was winning the game for us (which he didn't, the support and I did pretty good ourself).
But that begs the question, why is it a thing that a Trundle, Tahm Kench or Anivia can literally troll their own team, potentially killing them. There are probably more but 3 of them is enough to not be able to ban them as a solo player. At the very least I demand that every CC should be able to hit your own team, so it's a level playing field.

and using abilitys to screw allies over is frustrating but accomplishes exactly the same end result as picking any champion in the game and running it down mid.