Of course, if you took away the other 6,999,999,930 away, the 70 that "matter" would find life infinitely harder. So perhaps we aren't as pointless the title suggests.
When I saw the title I thought it was about social networks: there are 7bn people in this world and you only care about 70 of them. I imagine that could be equally true.
Forbes is pretty silly. Those people have much less power than they think. The #1 ranked person has a good chance of losing his job in a year.
You could equally read it as "There are 7 billion people in the world and these are the 70 people most dependant on them for their power, wealth and security."