Yes, sure but not everyone has the skills to get deleted posts, and if you're lucky you might be able to not be screwnshotted.
Some abuse is like some colleague or spiteful non-techy person who cannot or will not try too hard. It's just a matter of reducing those easy scenarios. No?? Why make it so easy?
Also mistakes happen. You could post a photo by accident, or accidentally has eg personal details or whatever the case may be.
It's not always as 'serious' as your post is making it. We're not all Mr Robot, some people might just accidentally post something and feel uncomfortable.