The call arranged in advance has replaced a doorway once available by chance.

Contact used to happen because people were nearby and doors were open. Now most of it has to be arranged, which means somebody first has to decide the other person is worth putting in a diary. That raises the threshold, and the relationships that suffer are the middle ones: not close enough to schedule, too good to lose. They disappear quietly for want of a doorway.

Lower your own threshold where you can. Ring somebody without arranging it first and keep it short. If dropping in is welcome where you live, do it, and make it welcome at your own door too.