So what you probably fail to recognize here is that consistent toxic behavior results in much more flags.
Typically speaking, 1 instance in 50 games is not going to be enough ever reach any sort of consequence. 1 in 10 games however, has 5 times the likelihood. What probably happened is you were toxic enough in a majority of your games that you were flagged to begin with, meaning each report thereafter had an ever-increasing chance that you would be "caught" in a bad situation. The difference is that the other player that you reported i'd imagine doesn't get reported all that often. Even if that's not the case, it doesn't excuse your behavior, which you have 100% control over.
Marginalizing your own actions through someone elses errors is childish and the literal equivalent of "Officer, I know I was speeding, but there were cars going faster than I was" or "well he got away with it, I should too". Just like in society, not every criminal is punished, some get away and skeet the system. NO system is perfect, and its ludicrous to have even a remote expectation of that. I don't know your age, but try to be "the bigger guy" or more mature in situations like this, as acting like a child and throwing a temper tantrum instead of reflecting on your own actions will get you absolutely nowhere in neither this game or life. Philosophical bullshit aside, man up, take responsibility for YOUR shit. If other people don't, that's their problem, not yours.
Not the answer you wanted, but its both reality and the solution. Also for future reference, "hate speech" is usually considered especially heinous- whether you consider it to be or not is irrelevant. I would point out that you had simply chose your words extremely poorly, and if you're going to flame no matter what in a scenario like this, i'd recommend changing your vocabulary, using mute, or just not typing. Never really solves anything anyways, right? Does it make you feel better? Does it make the other person feel better?