mstenta[m]: don't take this the wrong way - but if you think that then you haven't used these tools enough.  

The line might feel, in the abstract, all slippery.  But as soon as you start doing something with it, it becomes pretty clear what you should do and what you shouldn't.

It's similar to deciding what to post to AIM and how, and when to call, and when to text, and when and how to post to Signal, etc.

All technology develops natural nuance with use.