In other words, what yadda yadda yadda can convey is something  You and I know all the points that would ordinarily be inserted at this place in the conversation, so let's just skip it and move on.
Yadda yadda yadda can convey something different between people.
Yadda yadda yadda has a definitive meaning to all.
Adrin explained that the woman was alive and well but on vacation for a while.
There is a child sitting outside.
A tourist buying a hot-dog.
A man is singing.
A child sits in the snow.
A casually dressed orchestra practicing