Banning

Why is being toxic such a harsh offensive and dealt with such extreme punishment? I have mutable accounts (All of which are banned) and the thing I find gets you in trouble the fastest is being toxic. I have gone afk were iv been kicked out the game around 40 times and still not banned until I started ot be toxic, I Have fed none stop for around 70 games with just barley doing damage to the enemy and getting some cs and only recenty got banned , but god forbid you be toxic to someone who is doing anyone of them things . you will be banned within 5 games of talking like that , ( 6 accounts banned form being toxic) yea being toxic is bad, although iv never reported someone for it because if you cant take shit talk on the internet you don't belong here but why is it that people who are bad at the game cant be reported for that and put in a separate match making with others like them ? Why is it that people who go afk constanty aren't banned , just longer queue time. why is being toxic the super sin that everyone cries about?