Yes, the player community is still highly immature, toxic, and self-centered. Yes, a noticeable amount of players will rage in chat, afk, feed intentionally, and go on and on in /all chat with "REPORT MY TEAMMATE!!" like it really matters.
Riot did away with the Tribunal and now has the Instant Feedback System, which is a mostly automated report script that learns from itself and the community over time. When the IFS was new, toxicity was absolutely out of control and rampant, but now it seems to be getting much better at picking up toxic chat and behaviors. The best part about the IFS is that it judges without bias, so 99.9% of the people that get punished truly deserve it. Sometimes it does make rare mistakes, usually when someone gets punished for feeding even though they just had a really really bad game, but that's what manual reviews are for.
Riot has beefed up their policy on what is and is not toxic, so now people who use the N word or other racial slurs, homophobic or sexist slurs, and encouraging others to kill themselves (kys, get cancer, etc.) pretty much get a 14 day suspension with only one or two offenses. Also, crying out for reports on players is considered toxic (Report Calling), and stupidly unnecessary shit like "ggez" or calling people bronze or bronzies can be reported.
So yeah, Riot is at least trying to get on the right track as far as player reform goes. The negative side of the IFS is that it does not understand context or sarcasm so you have to be careful with saying things that can be perceived as toxic even if you didn't mean it that way. For example, if you're playing with a 5 man premade and you're telling your friend in chat who's carrying that they're trash and the worst insert champion name here in NA and someone on the enemy team reports you out of spite because you whooped their ass so hard, the IFS might look at that chat and determine you were toxic even though it was all just sarcastic humor with a friend.
Also, a lot of people get punished for retaliation, such as when someone is being toxic or trolling and they say something to defend themselves. The toxic troll reports the person who retaliated, and then they both get flagged by the IFS. So now the only thing to do is ignore the morons, mute them, mute their pings (THANK YOU RITO!!), and report them after the match. Action will be taken against a person'a account with as few as three reported matches, less if they are guilty of bigger infractions.
Anyway... tl;dr the League community is slowly improving, just mute and report.
