Riot why does it seem like certain troll behaviors are bullet proof to bans?

Troll picking to actively hurt a team just seems to get a pass. Whether its because someone got irritated that someone else wanted to go into a lane or because people get more enjoyment out of frustrating their own team and then dropping reports at the end once they have pissed everyone off to such an extent that they just rage out.

I get that its policy to not enforce meta but at the same time the game lends itself to certain roles. I mean adc needing farm to get items to become strong has always been built into the game i.e. kogmaw is not close to the usefuless of a jarvan if they both have one item or the utility of a thresh before kog'maw gets going. Anyways point being when people make picks to actively hurt the team whether its because others have already selected champs or "called" lanes it seems like there is a free pass for unsportsmanlike conduct which as far as I know doing something for the sake of frustrating other players or sabotaging your own team for personal amusement is unsportsmanlike. So when someone goes adc style champ and a troll goes something like another adc or a wave clear champ and isn't playing to last hit as much as deny farm to the guy trying to play adc, it just seems like they are immune to any form of repercussions just because any moderation that could be construed as enforcing a meta is avoided. (generally I play solo lane champs given the choice but its pretty noticeable when so few people want to play a support style champ and adc's get screwed so often because of it game after game).

Another issue is in normals/blinds where the someone will state "its just normals" implying that they are not putting any effort in trying to win as if it were ranked they would not be playing in that manner. I mean it is a team vs team game and even not taken seriously at, part of playing the game is trying to win...

I mean if I'm playing a casual game of baseball with friends I still swing the bat I don't just say "meh its fine its not as if it matters."