Allow Us to Flag Spite Reports
There is a problem with toxicity but also a problem with another form of abuse, false reports. Riot has no one analyzing the veracity of reports, it's just an automated system that evaluated report frequency, checks chat for basic trigger words and has little intelligence. There is no Tribunal anymore. Even quoting toxic players can flag it.. You are at the mercy of the system and false reports, while usually weighted less from those frequently abusing the feature, still have some weighting.
Of course, ideally there would be something like Tribunal where impartial peers can evaluate the evidence in more complicated cases. However, in the mean time, I wish there was some way to flag a report as "contest" and have it investigated more deeply. I've found many toxic players spite reporting when they get the report notification. It's gotten so bad that I actually have to wait for them to leave the room before I report them. I'm guessing they know who it is by comments such as "I've muted you so please only use pings." or "Please worry about your own lane and just let me play."
Some people might think that now everyone will try to contest every report but many are incontestable anyway by using certain racist or homophobic terms. Furthermore, I think most players realize when they're toxic and have no chance for a contest to be successful. I'm pretty sure the player typing "open mid, gg, afk - report bot" has no qualms about breaking the rules.
Another way to tackle this is to punish people for rageports so they don't distract the system from the real problem players. I don't think there is any realistic consequence to false reporting right now (beyond report weighting getting lowered eventually). The problem is that by the time a report from this player is worthless, he may have already tipped the scales to punish someone who was overall not a problem. Moreover, some players don't consistently make false reports so their overall report weighting might still be pretty normal.