There's also this aspect I feel, that I posted about previously, which is kind of anger and resentment at people who use social media, who post about their perfect lives which cause others to feel badly about their own. That bad feeling can actually go as far as depression:
"The irony of
Facebook is by now known to most. The “social” network has been linked to a surprising number of undesirable mental health consequences: Depression, low self-esteem, and bitter jealousy among them.."
New Study Links Facebook To Depression: But Now We Actually Understand Why.
I can't forget the actual male friend of Shanann who early on made a statement to the media that her life on social media was so perfect that he "had to block her" . Which I continue to think is quite bizarre but indicates the level of jealousy and rage people have at those who are excessively positive and post wonderful things on FB. (I mean just get off social media or unfollow the person).
That coupled with societal attitudes about femininity -what a good mother looks like, what a good wife looks like - I think combine to cause harsh criticism of a dead woman.