Let us just say that not all friendships, even the ones that start out strong, end up having the same depth to them because of the loss of shared context (e.g. moving out of the same city for jobs, new responsibilities caused by marriage etc.)

In such cases, there's still some reason for the two people involved to at least have a general idea of what's going on in other people's lives, and even reach out should there be something significant, such as a birth of a child or a loss in their families, etc. Without the broadcast aspect, once communication has ceased for some amount of time, it is very difficult to restart it, at any level.

As an introvert, I still find broadcasts weird, because there's that tingling notion that people wouldn't care anyway; and was one of the reasons I ceased to be on social media many years ago. However, I at least understand why some people choose to do things differently.

(There are similar anecdotes throughout this thread, I'd encourage you to read it for perspectives on this matter.)