Why is seeing sexual content bad for kids?

I’m not questioning whether it’s bad for kids, it’s pretty obvious it is, but like there have been numerous societies where due to space constraints one ended up sharing a room with your parents which meant seeing em go at it now and then. I think that the difference is probably that then it wasn’t an act that by merely being visible to the child involved the child. Cause then you were all sort of crammed together and like tuning each other out/ignoring each other was kinda the point but here and now, you don’t fuck in front of your kid unless on some level you *want* your kid to see, which sexually involves the kid who can’t consent due to the power differential and so that’s fucked up, similarly, you don’t show a kid porn unless it’s somehow tickling you to show them porn, which then becomes an aggressive act again. Which is why like kids who walked in on their parents by mistake are grossed out but not eternally traumatized, but kids whose parents intentionally got it on in their presence are. Ditto for kids who managed to find their parent’s stash of erotica vs kids whose parents intentionally showed them porn. Does that make sense?