The concept you're missing is that a barrier to communication, like sending the fax, forces one to organize their thoughts before impinging on another person's time.

So while digital communication has a lower round trip time, it also has a lower barrier to entry, which means you get more communications and they're less focused.

This leads to situations like my inbox, with 50 messages a day that are parts of huge unfocused threads and it can take 5 minutes of diligent effort to find out if my attention is even required, and at that point my 'action' will probably be to reply to the thread asking for clarification, setting off the same bullshit task for all the people CC'ed