The 14-year-old sent tweets to American actress Lili Reinhart and YouTube star Salice Rose, with one saying: “I can’t do it any more.”
Molly’s father, Ian Russell, was taken through the posts from the witness box on Thursday, where he said: “I believe social media helped kill my daughter.”
He said the messages sent to high-profile figures were “particularly prevalent on Twitter”.
Mr Russell told North London Coroner’s Court that harmful and “normal” online content would have been “conflated” in a 14-year-old’s mind.
He was asked about his thoughts on the effect of Molly accessing “harmless” content on social media platforms, such as posts about fashion and pop music, by the family’s lawyer Oliver Sanders KC.
Mr Russell told the inquest that “digital technology can be brilliant”, but the difference between the two types of content “would be very much blurred” for his daughter.
Giving evidence in the witness box, Mr Russell said: “I believe social media helped kill my daughter.
“I believe that too much of that content is still there and I believe there is a lack of transparency.
“Children shouldn’t be on a platform that presents a risk to their lives.”
His remarks were made before a senior executive from social media giant Pinterest later told the inquest he “deeply regrets” and is “sorry” for content viewed by Molly on the site before her death.
Judson Hoffman, the company’s head of community operations, admitted emails sent to the teenager such as “10 depression pins you might like” was “the type of content that we wouldn’t like anyone spending a lot of time with”.
Mr Hoffman was taken through a vast number of “disturbing” images Molly had interacted with on the site relating to self-harm, suicide and depression.
Pinterest describes itself as a “visual discovery engine for finding ideas”, where users can save the “pins” they see to their own “boards” – said in court to be akin to creating a collage.
The court was shown two streams of content the 14-year-old saw, comparing the material she viewed earlier in her use of the platform and in the months closer to her death.
The inquest, which is expected to last up to two weeks, continues.