Well look at it this way
When you get banned/punished for toxicity you clearly can say you were not it. You are clearly pissed about it, as words can be read in so many ways. One way you're not toxic, One way you are Toxic
but intent feeding is a tad more understandable by a user
end a game 0/18/0 have 6 tears in a 25 min game, I mean yeah that is feeding no matter how hard you try to convince someone else.
Feeding is also harder to detect is my guess by riot, as bad games happen yada yada
So feeding cases are clear cut cases to all(or should be)
Toxicity cases: people think what they say isnt toxic so they argue their case, and usually are never happy
so they come to the forums to rant about how its unfair, the bs system, etc