Welcome to League of Legends. The most abused, broken system, where a bunch of people who can't take anything criticism say to them no matter how nicely you try and say it. Heck, don't even use chat because you will get restricted. System is so horribly designed and broken, being open for abuse that it's not enough that the "offended" person reports you. No, they go on campaign and try to get EVERYONE, even the other team to report you. I don't even use /all chat most the time but the "I'm so hurt" player will sure try and get them to report you.
Why, you ask? Because they know the system is horribly broken and doesn't actually get reviewed. This has been proven so many times. They have a ridiculous algorithm that decides if you were being "toxic". So the more people you get to report you, the better the chances the "hurt" player will have to use the broken system against you.
But Riot will tote bogus statistics about how only 3% of playerbase is toxic blah blah... yet the way there system works would make you think everyone was. I went a full 3 week stretch. THREE WEEKS where virtually every single game was trolled with AFKer, toxic players, trolls, feeders etc... and what happens. If you don't want to stick around, or dare to try and rally the team by speaking strategies in chat.. BAM reported.