Only thing I have to add to this: Pretty much anything beyond two people is going to have some form of toxicity, small as it sometimes is (and large too). Pretty sure that if Candy Crush, for example, has some sorta chat feature you'd see plenty there as well and thats supposed to be rather casual to my understanding.
By the same token you'll also get niceness that goes beyond what you would expect even without expecting toxicity from everyone you meet. Roll of the dice and all that.