I do believe that the first rule is that Riot can and will punish you [Applicable via warning, mute, low-priority queue, temp ban, permaban, or any other applicable account restrictions] if they deem that you are toxic to the game's health. All of the rules are derived from this, the goddamn Summoner's Code is primarily derived from that, and it's been their modus operandi for the entirety of League's history. It's what they do to champions and players alike. The rules and their punishments are not set in stone (except for a select few, such as: You cannot knowingly and deliberately imitate a Rioter in a realistic manner (jokes=okay, actually pretending to be a Rioter=not okay)), and have never been. They can be as lenient or strict as they deem the situation warrants.
Riot's policy of not banning for being off-meta is to prevent people from being banned for trying something new that looks like it might work, be it
on
,
jungle, or
support (all things I've tried, been yelled at for, and found varying degrees of success. The first one=very good, second is iffy, PLEASE DO NOT DO THE THIRD ONE EVER! IT IS TERRIBLE!). Being off-meta is perfectly acceptable, otherwise you'd be banned for playing a champ that isn't considered "OP". But committing suicide in champion select, by deliberately picking something that obviously won't work, THEN commencing to fail to play properly, and fuck over your team? That, if nothing else, is intentionally sabotaging your team.
tl;dr: I agree with you, OP, I'm just ranting about what idiots have said, and elaborating on your point.