No child was ever damaged from getting a glimpse of a very normal adult human interaction. When young people are old enough to be curious about this (e.g. they're looking to access spicy content), the correct approach IMO would be an open dialogue from their parents and extensive education/access to age-adapted materials in school. There is nothing dirty, shameful or obscene about sex, it's a natural process. It's also not scary, and it can be practiced safely and responsibly.
I also suspect it’s at least partly linked to declining reproductive rates. It’s the same as freely available sugar. Human ape brains weren’t evolved to handle this sort of easy access high dopamine stuff.