I've got this page bookmarked on my phone for three days now. Thank God I'm finally reading this now. I guess the social media companies understand the psychology you explained about having a cue to stop. So they've totally eliminated all the possible cues feeding us with an unending update in form of new post. Have you noticed that you cannot get to the end of your news feed on facebook? It keeps refreshing it.
Instagram was my worst addiction and also the first social media I deleted from my phone.
I saw a video on YouTube the other day, the man talked about how dangerous the social media is but at the end of his video he asked the viewers to follow him on twitter, like his page on facebook, subscribe to his channel on YouTube and finally they can follow him on instagram too. I think there are too many hypocrites trying to preach people not to use social media and this is proving difficult.
My suggestion is to have more people know the good part of social media and how to engage in content that will benefit them more.
And for those of you having problem to know when to stop using social media. A friend of mine told me about an app that helps you stop social media depending on the options of your settings. I wish I knew the name but a search on Google will help you out.