False Reports/Defending Ourselves from ALL CHAT/TEAM CHAT

Okay, first things first, the question I have is: "Are we allowed to defend ourselves if our team/enemy is insulting us that offends us?" For example, races, stereotypes, sexual orientation, etc. I get that there's the mute feature, but what's the point of that? If it's already making you play worse? Also why is it that people say in all chat, "Report [blank] for feeding. I'm pretty sure you can't get banned for feeding. Like I had this one bad game, where I went 0/8 in lane. But I'm not running it down and intentionally feeding them kills, I am just getting outsmarted and outplayed. Another example would be, "Report [blank] for AFK." But clearly they are still in the game.