I do feel social media is sort of running the childhood. Though not saying that social media is execrable but it is definitely not doing a lot of good to the children. Children become addicted to such a level that if they some fine day wake up and see their followers count has gone down, They run into depression. Also dating on social media have unpleasant effect, (though very rarely we find it working the right way). Nowadays children don't really realise their limits and due to this social networking is earning a bad name.
In order to say that you can ruin childhood, There must be a correct type of childhood. Otherwise, A child who is addicted to social media is not ruined but just unique. It is impossible to create a universal definition for a good childhood, So it is therefore impossible to ruin childhood.
I'm 17 and as a 10 year old i have bin exposed to porn, Graphic images and fake beauty, I'm perfectly fine I never screamed or said "ew" at any of those things i listed, Kids honestly don't need parents watching their backs every two minutes they find out one way or another! If your going to go all out and scream about how dumb 9-14 year olds are, Go ahead but they still have the ability to understand sex, Marriage, Abuse and also the internet. When i was exposed to that sort of stuff i was perfectly fine i was never scarred as some people would've thought I saw it as perfectly normal, In my head to me if i was going to say "ew" at those things i was practically saying ew to myself, (hopefully) everyone will somehow have sex, Masturbate, And do a hole other ton of crap.