In most cultures people are raised such a way, the naked body is something "forbidden", "bad", "immoral", "shameful", etc.
That's only part of the issue.
Another part of the issue is that in terms of having sex women have an ultimate monopoly - especially in the Instagram era they've taken the position that if you're born a female you can ultimately get the right to "sell" access to your body to the highest bidder. Nothing needs to be done to claim that, just being born the right sex.
These two things lead to the conclusion that nude pictures/videos first of all, are for sale, second, can cause a lot of drama and moral pain, and as a result can be used for blackmail.
If we had a society where the naked body was not something immoral, where sexes were truly equal (aside from strength and mass) and people were equally worthy of one another, there would be no such issue.
There's no shame in being naked. There's no shame in being seen this way.