The problem to me seems to be Facebook's pervasive "friend" lingo (certainly not true in most cases) and a heavy cultural bias in that article.
I'm sure I don't have more than five of the "most intense" sort of friends, but there are a lot more people than that who I care deeply about. Relationships that are very close when 'active' are presumably a different category - I think most of us have old friends and family who we feel strong connections to, but don't actually talk to on a daily or weekly basis.
Time places hard limits on how many people we see frequently and at length, but frequency and quality are fairly independent axes. I'm assuming "most intense" requires a high score on both.