Not at all surprising given that base instincts come from genetics and genes take tens to hundreds of thousands of years to change significantly.
To put in plain terms, we keep inventing far better "spears" (including kinetic, bio, and chemical) that allow one to kill many, while still behaving like cavemen.
Thanks to the Balkanization of our media landscape, and social media targetting: "a slick turn of phrase that appeals to our base instincts/caveman brain" can be tailored just for you. It has never been easier to make us behave in crazy ways.
I genuinely believe that the existing incarnation of "social media" could lead to the death of billions of humans.
To your other point, I have a friend who thinks social media and online porn drive fetishism, and that fetishism drive a lot of the new 'illiterate' political movements. I don't think I totally agree with him on the illiterate part (I mean, Renaud Camus certainly managed to read Maurras before paraphrasing him, in an objectively worse way, sure, but still), but I have trouble arguing against his other points. He also thinks that this fetishism taken too far will push people towards a death cult, and kill millions
For example, "self-domestication" by executing or ostracizing individuals that don’t fit into the culture.
In modern times it is more likely that culture and education augments genetics such that your violent tendencies are repressed, you are brought up leading a soft and comfortable life, taught to be polite and kind, etc. Contrast to maybe someone brought up in a warzone or some other place.
I mean post apocalyptic shows like the walking dead express this quite well (at least the first few seasons) where once society falls it's just a free for all and back to our roots again.