Why League Can Be Stupid

So I was just in a 4 man premade, we get assigned mid, top, bot and support. The random gets jungle so they asked mid for their position, mid declined, jungle bans our mid's pick, locks in lux, swaps smite with barrier and says "I'm in a bad mood today so." I got mad so I banned the Yasuo they were going to play and called them out for being toxic. Then when match starts lux pretends she did nothing wrong and claims my team is trolling. I know riot won't do anything because they don't keep records on prematch so that's why it's dumb how those kinds of players get away with their actions but not someone who uses swear words or something.