I don't think toxic people are going to change their behaviour if the boards tell them to.
Everytime you check the front page, you always see at least a few posts like this one here: https://boards.na.leagueoflegends.com/en/c/player-behavior-moderation/Etgm6EvA-stop-saying-ggez
While I agree that this is shitty behaviour and that these people are being dickheads, I don't really get how posting something like this on the forums is going to change anything about that.
You guys have to realize that these people are stuck so deep into their bullshit that they don't realize how much of a dick they are. When two people are fighting in chat over nothing, I often tried saying things like " it's not even 5 mins in and you are flaming each other already? " and the universal response would be something along the lines of " I'm not flaming, I'm just telling XY that YZ ".
The overwhelming majority of toxic people are reality deniers, often times children or teenagers without the experience or brain capacity to realize it or workless basement dwellers who have nothing better to do than play League all day, which is why you encounter these people so often to begin with.
I know this is going to sound pretty cliche but the best move is to just not think about them and ignore them, whether by muting them or just not reading chat and then reporting them at the end of the game ( Which a surprising amount of people don't do. Seriously, take the time to report dickheads. ). They want someone to pay attention to them or they're just irrationally venting their accumulated anger into chat and you can't expect an angry person to be reasonable.
If you really feel like making these kind of posts then go for it, it's a nice way to vent your frustration over the everyday idiots you encounter in League. But realize that it won't really serve any other purpose.