Witness to mundane things

The movie "Shall We Dance" happened to have a dialog that caught my attention ..
(Movie courtesy of rest and recuperation following a bad bout of food poisoning)

The dialog mentions that people marry to have a witness to their lives .. so that their lives don't go unnoticed. The promise that the most minute and mundane bits of the lives will have a witness and a viewer ..

Isn't it also the reason why people "Twitter" or update/read status on "Facebook" or Blog?
To have witnesses to their lives (or be witnesses) ..