I agree that part of the addiction may come from fear of simply being alone. With facebook and messenger you're always just a tag / msg away from a friend or someone to talk to...
many of us see in terms of eye health and the minds of children who are addicted to technology makes them sick, they can not be away from the technology (mobile phone), soon enough then they will cry, if they do not use it in a day they will be lonely.
I agree with your satement that part of it is simply the fact that human beings don't like to be 'lonely'