Seeing a lot of people get perm banned when they're only reacting lately

I have a friend who is the sweetest person, hardly curses and has been perm banned twice for only reacting to people doing trolly things. (Strikes every few months from the start of 2016) The only real thing they did wrong would be asking others to report and the occasional getting frustrated and cursing, which I feel like it's fair for them to get annoyed at least every once in a while, it does build up after all. This is just one example.

Why is riot even banning people for chat-related things? Give them a permanent chat mute if it is really that bad, save the banning for people griefing.

Also, this is a reaction to players griefing. I see it in a lot of league games that I play, so shouldn't riot focus on the cause instead of trying to cover it up? Yes people overreact and start to harass and tilt over the mistakes of others but when games are usually decided quicker than in the past and you come across someone who doesn't know things they should know for the elo or are simply doing trolly things or just ignoring you, you are powerless and usually if you try to play around the people playing properly the other person will start to harass you. You also can't try to give anyone tips or lead the game because again, most people start to harass you or ignore it. I play jungle so keeping track of the opponents jungler is part of my job - I can ping and I can say in chat where they most likely are if they have any clue what they're doing and half the time it goes completely ignored or people harass me for it. I don't think the majority of players care about playing properly/improving/winning so much as opposed to just being in a competitive environment so I tend to find myself fighting the urge to lead via communicating because it just makes things worse which I feel is backwards to how it should be.

Why do these players have security over someone who is frustrated at them for not playing properly?