ShitRedditSays, and the "most toxic" subreddit in that result, is actually a joke subreddit. It's a "circle jerk" where everyone flips around the standard racism and sexism (so sexism jokes against men) etc. "breaking the jerk", actually taking it seriously, is a bankable offense. I think this makes their analysis flawed. If you were to look at spelling and grammar, you might conclude that people on polandball are th…
This is 100% the case for newcomers to the subreddit, which is already enough of a reason for it to be considered toxic. But it is also true if you are not new to the concept. There is plenty of hatred and anger in the SRS network of subreddits - read the other SRS* subreddits to see - and shitredditsays is where they are allowed to vent it, under the guise of sarcasm.
Sarcasm and satire can be valid and honest. But when an entire community like shitredditsays does nothing but that all day, every day, then it's an convenient place for actual hatred to be expressed.
Sometimes - rarely - there is something egregious enough that it makes sense to mock it and be sarcastic about it, even harshly so. But if that's all you do all the time, like shitredditsays - and tumblrinaction, and others - then you quickly become toxic. A community dedicated to hatred of other groups can't avoid becoming toxic.