Honestly, having played with Rioters in the past, they go through the same experiences we do. Heck, most of the time it seems like people go out of their way to flame Riot employees more, which I think speaks volumes about the bad apples in this community. I think that the place where Riot is running into the most problems with this is that they have to find a balance between justice and fairness. Sure, they can whip out the ban hammer on people for being toxic, but if they do so too willingly they risk alienating their audience.
What I find the most frustrating about having those individuals in your games, is less that they don't get punished, (we barely have any knowledge if they do other than the pop up, and even then it could just be a slap on the wrist) but more the fact that we're meant to prove ourselves as players by climbing a ladder of solo/dynamic queue, but one random person feeling like a troll can ruin the experience, which has further reaching consequences than just that game. Not every person will say "Oh well, just that one game," it can ruin an evening of gaming for some users, and it becomes a cascade where they eventually hit their "I don't care anymore," point and begin forcing the behavior upon others.
We as players have little to no control over people doing this to us in ranked games, and it really sucks that we get into promotions, series, etc. then one person can ruin everything we worked hard for.
Point is, there's always going to be bad apples, and the unfortunate thing is that good people suffer for bad people's actions. Maybe in the future Riot will introduce some sort of tool that rewards us some LP back if there's a clear problem with a player on a team, instead of gouging our W/L because one guy is having a fit of rage.