The 14-year-old girl viewed material about self-harm and suicide before she died in 2017.
The father of 14-year-old Molly Russell has told an inquest he believes social media was a key factor in her death.
Ian Russell said safety measures, such as speed limits on roads, were accepted in the offline world but “are not put in place in sufficient quantity in the digital world”.
Molly, from Harrow in north-west London, died in 2017 after seeing content about suicide and self-harm.
The inquest also heard how Molly tried to ask for help from celebrities.
Mr Russell said his daughter had reached out for help on Twitter to personalities with thousands or even millions of followers, who would not even necessarily notice a tweet from someone like Molly.
He added: “She was calling out to an empty void.”
North London Coroner’s Court examined how Molly used an anonymous Twitter account to message influencers and showbusiness stars.
One, sent to US actress Lili Reinhart, which was read to the court, said: “I can’t take it any more. I need to reach out to someone, I just can’t take it.”
Mr Russell, who previously told the inquest he was shocked that “dark, graphic, harmful material” was readily available to be seen by children online, questioned how Molly knew “how to get into this state”.
Mr Russell said he found it “hard to believe that some of the most powerful global brands in the world” could not find a way to help prevent such content reaching vulnerable people.
When asked about his daughter accessing “harmless” content on social media platforms, such as posts about fashion and pop music, 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.
He told the court that harmful and “normal” online content would have been “conflated” in his daughter’s mind, before he concluded his evidence by saying: “Children should not be on platforms that are not safe, that present a risk to their lives.”
Judson Hoffman, head of global operations at the image-sharing and social media service Pinterest, told the inquest that the company was “here to learn and help through this process”.
People over the age of 13 can use the platform and Coroner Andrew Walker asked if the company distinguished between children and adults when accounts were set up.
“No, we do not,” Mr Hoffman replied.
The lawyer for the Russell family, Oliver Sanders KC, asked Mr Hoffman if Pinterest’s business model was to encourage users to spend more time on the platform so advertisers would have more time to display their products.
Mr Hoffman said: “That may be so. Pinterest, from the time that I have been there, it has been a slightly different tack – it is not time spent on the platform, but time well spent.”
He added that it was “primarily for the user and secondarily for advertisers”.
If you’ve been affected by self-harm or emotional distress, help and support is available via the BBC Action Line.
Follow BBC London on Facebook, Twitter and Instagram. Send your story ideas to hellobbclondon@bbc.co.uk