ah, any non-specific topic is going to be hard to answer because Riot operates under a "community decides the rules" mentality from what I've observed
obviously there are some things that are set in stone, but the "unsportmanlike conduct" or "refusing to communicate" are relatively left to the community. Players in like, the Korean server, might be more tolerant to out of meta picks and players that tend to split push, so players like that will naturally recieve less reports and the Korean server will recognize that those situations are acceptable to that community an so it won't punish anyone.
In NA, we might be more prone to report out-side of meta picks and players who don't group and would rather split push, and so the server recognizes that the majority of players don't approve of this style of play and will punish those who do so in order to maximize happiness of it's players. That's why someone like that Singed guy got banned from sheer reports (although imo it was deserved because he was playing like a prick and at the cost of his own teammates, actively screwing them over for his own slight benefit). To me, his situation shouldn't be "why was he banned?!?!?!" but a "maybe the reason should be 'unsportsmanlike conduct' and not 'refusing to communicate' riot".
Of course, the majority of what I said is simply guesswork based on observations and trying to fathom how Riot runs their servers, so I could be completely wrong. That's just how I imagine it playing out and I can understand why they'd want the system to run that way
