a) I think you're right that the focus should be on "is this detrimental or beneficial, overall, to what is important".

b) The assumption that such friendships must be a problem or an early warning sign of problems, reminded me of something I wrote a few years ago about heterosocial and homosocial subcultures (though Google tells me that in a mere four years since the last time I searched for the word "homosocial", it has acquired other meanings than how I used it).