"That's just society" is such a bullshit and lazy response to stuff like this, I don't even know why people bother to type it out. In the real world if you went out and said even half the shit I read in comments people would think you were part of Westboro or something.
You're absolutely correct that the comments and other stuff are reprehensible.
You're absolutely correct that if people acted like this in 'real life' they'd be shunned, if not punched in the nose.
Where you're wrong is linking it to gaming. Go to the comment section on youtube for anything -- beatboxing, dancing, music, 'challenges', etc... and you'll see the same exact behavior.
Go to ANY political article ever and read the comment section and you will find the most vile, disgusting, reprehensible comments ever -- ones that will give these a run for their money because some of them are clearly serious and not arguably trolling. Articles on shootings, robberies, or the weather -- anything that has any political connotations, will be full of racial/ethic/gender based slurs thicker than you can believe.
The internet is anonymous and we've learned anonymity breeds toxicity. Even when not 'anonymous' (such as facebook login required) you'll see people making horrific comments on various topics -- at least, I'd hope they didn't say those things out loud. This is a problem with humanity, and our society, not specifically with gaming. It's not a 'bullshit' and 'lazy' response to point this out --- if anything it's lazy to attribute it to 'gamers' when it's a widespread epidemic online in most forums/comment sections.
I am not defending a single person posting that toxicity. It's foul and disgusting and makes the world a worse place. I don't understand why people feel the need to poke hate at people, or make death threats, or anything else. But as long as people keep pointing the finger at a specific subgroup (in this case, gamers) rather than study the issue as a whole, it causes unnecessary pushback as all the normal, sane individuals in said subgroup will feel attacked as well, which you see in every single thread like this. We do not pretend that vile racism and sexism is an issue for 'people into politics' even though political comment sections are thick with it... we understand it's a bigger issue, and this is an extremely deep rooted issue. It's either a flaw in our society, or humanity in general. It's foul and toxic. But it is not, sadly, limited to one tiny demographic no matter how much we may hope it was.
Also of note, any 'hot button' issue like this will pull people out of the woodwork who don't care what the topic is, but just want to agitate people. If people were bent out of shape in a cookie forum, they'd be there hurling insults. Assuming everyone saying everything is part of the actual demographic is flawed as well... this kind of thing brings out the worst in the worst people.