There's a character in the third major arc of YYH that basically gets black-pilled after he's forced to watch a video compilation of every atrocity mankind has ever committed called "Chapter Black." This becomes his motivation to open up a door to the underworld that allows demons to pass into the human world unimpeded.
If that isn't a tale of morality for why you shouldn't be constantly online or reading the news I don't know what is.
YYH also came out in 1992, so like... this warning was pre-internet. Imagine not yet having access to *all human knowledge* and going "This is kind of a lot. Maybe don't take it in all at the same time and out of context."