[happytoexplain]

Personally, I think it's probably less likely that the world has somehow lost comprehension of an entire "obvious" concept, and more likely that people would have always reacted more or less as they do now, and what has increased is the quantity, extremity, and sincerity of hateful expression (in general, not just legally defined hate speech), partially because some people are becoming more loudly hateful, and partially (mostly, I hope?) because mass communication is so dramatically different now.