UNACCEPTABLE - It is becoming more and more common...
For people to blatantly lie through their teeth about what their teammates are saying and/or doing in order to get them reported.
Riot at some point you have to accept that you need to do SOMETHING to improve the community other than let them police themselves because it's not getting any better. It's pretty much accepted that playing well in-game is the only thing that matters, and being a dick to teammates in any other way either doesn't matter, or is applauded. I do not enjoy playing a game only to have a teammate spam ping me all game long because they want to place blame on me. I do not enjoy teammates lying and saying that I am throwing around the Nword or that I am intentionally feeding just to get more reports on me from the enemy team. I do not enjoy having OTHER teammates back them up to support said lies, all because I am having a bad game so they are banding together to try to get my account banned.
This is basically commonplace at this point. It even seems accepted by most of the community. Your report function has become nothing more than a tool for harassment because YOU, RIOT, do not take false reports seriously.
Your "no context" approach on reports is also harmful for a fair justice system as it basically means "if you aren't a saint you will be punished if you are not a good player". I say that as somebody who doesn't get punished because for the past couple years I've tried to avoid saying anything negative in chat, because I know that as a bad player I will eat 5x more reports than anybody else. Meanwhile kids who are great KDA warriors abuse and harass their teammates all game long, but as long as they manage to pass the blame onto another teammate, they will not eat any reports themselves because PEOPLE. DON'T. USE. THE. REPORT. FUNCTION. PROPERLY.