The most generous assumption is that they use statistics to determine correlations like this (e.g., deleted selfies resulted in a high CTR for beauty ads so they made that a part of their algo). The least generous interpretation is exactly what you’re thinking: an asshole came up with it because it’s logical and effective.

Either way, ethics needs to be a bigger part of the programmers education. And we, as a society, need to make algorithms more transparent (at least social media algorithms). Reddit’s trending algorithm used to be open source during the good ole days.