Here's the thing that gets me... you describe things as being far worse than I ever experienced, and even watching streamers, it's worse than what they see. I even moderate for a female streamer that uses voice chat, and there's far less toxicity than you're describing. Sure, people are sometimes mean to each other or blame each other, but it's almost never racist or homophobic. In other words, unless you're exaggerating, you seem to be trending well above average in toxicity.
Now, over the years, if there's one thing that I've learned, it's that if someone is seeing far more negativity than others in similar, there's a possibility that they're part of the problem. It's hard to really know because I only know what you've talked about, but you've provided two examples that you should have probably handled differently. To the hecklers, you should've just muted them on voice if their laughing was annoying, and well... probably shouldn't have called the person an idiot. Just report and move on.
So, I guess my question is... have you ever been banned from chat or voice chat? ...or even had a smaller full-game ban in the past? At least from what I've seen, it's rare for Blizzard to outright ban someone unless their actions are quite egregious, they're hacking, or they've had multiple offenses.
Refrain from the 'blame the victim' instinct. Part of your post is valid - and the answer as far as I can tell is, two things.
One is that I played a lot more than most people. I was up gold player level, which I'd rarely see in my level (high bronze - maybe that's another factor). The other is the huge hostility against Bastion players, more than any other hero.
So, the toxicity I describe wasn't 'normal' - I could play 100 games and not have one like that - but even a small percent add up. Did you repeatedly have groups of enemies who recognized you at the start of the match and were already hostile, and then spend the match doing nothing but focusing on you, to the point of spawn camping you and making their team lose? Probably not. I did.
Yes, I had full game bans for chat reports in the past - it's just an ongoing situation, not much I could do about it but reduce the number of reports if I totally stayed out of chat, but I was the shot caller basically every game, so that wasn't much of an option. Enough with the 'it's your fault' stuff though - if you have more reasonable questions though feel free. It's a lot of toxic players.
But to your point as well - those are NOT exaggerated, they're just some of the worst cases. Probably more than half the time someone used the n word or a gay slur and I said "do not use slurs", they stopped - but a lot of times, they'd then explode with them where I might call them a bigot, an idiot if needed, and say I blocked and reported them. Not much doubt they'd report me.
The issue isn't so much that an automated system led to a ban, it's Blizzard's negligent, careless handling of the ban and any appeal, including simply lying. As I said, it's even their official statement that they wont even consider an appeal.
I don't know what to say about the fact that I think it was possibly thousands of times I reported people for using slurs, and not much question many thousands of times for excessive insults. Even if there could be long strings of 'nice' games between them.
I do understand that my experience wasn't typical, in terms of the numbers, and that it raises a question. I think an important thing is that I would not tolerate the toxic behavior, most did. So I'd get the reports from the guys mad I told them not to use slurs. And I'm fine with that.