Actually it's the typical Slashdot response - half read a summary, misinterpret it and go off in full outrage based on your misperceptions.
The coroner didn't say that Facebook was THE cause. he said it was A contributing factor (not the only one, but one of several).
It's easy to draw parallels. For example:
Yes, obese people could control their intake and exercise more, but some physically/emotionall cannot.
Saying that having a diet full of foods swimming in growth hormones, sugar and corn syrup is a contributory factor does not negate this.
Living in a society*** where profits go before quality and a 'free market' which amplifies this by making such foods widespread and undercutting healthier choices will lead to a cycle where the less well off get trapped with such a diet.
Replace poor quality food with poor quality media and the same scenario applies.
Having social media driven by profit for a near monopoly; having that media geared up with algorithms to reinforce 'engagement', knowing that it can lead to unhealthy outcomes, yet pressing on with such practices and targetting the young, impressionable and vulnerable is,in my view, definitely a contributory factor.
Now, if Facebook were smart (asking them to be moral is a stretch), they could send a blend of "depressed? here are some support/help lines" and "I was in your situation but I'm much improved now, here's my uplifiting story" messages. It may even help them improve their image and thus their bottom line.
***Thankfully the UK does have some good food standards - but I'm sure that Jacob Rees Mogg and his cronies are working hard to undermine them.