Clearly, FB and others 'hook' you in to get you to spend more and more of your time on there so they can get more advertising revenue by telling their revenue providers how many hours you spend on there. The more hours, the more money they can command much in the same way as ITV and others. When they can boast massive viewing figures their advert fees go up.
Problem is, it does make some people anti-social in that when in real company, they keep looking at their phone every time it pings. They cant resist it as the 'like' message they just got is far more important to them than having a conversation with you.
Of course, when tackled, they all deny it just like the bloke who 'likes a drink' denies he has a problem with alcohol.