When you're a toddler, your brain is strongly updating all the weights and biases encoded inside the lump of goo behind your eyes. It's literally a years-long neural network training exercise, with all sorts of back-propagation and pruning. I can imagine very strong feedback loops between algorithmically-generated content and neural development with weird side effects.

I don't care that the content is violent per se. Whatever. We're robust against that. What I do care about is how the content is inhuman and engagement-optimized. We, as humans, are as defenseless against that sort of thing as the Dodo was to hunters.