That article is misleading. It mentions several times that you shouldn't blow your nose while you're sick and at the very end says that "The proper method is to blow one nostril at a time."
I mean, I always blow one nostril at a time, it's nothing new
And it contradicts the title
And I mean if your nose is stuffed, it is not healthy to breathe throuigh the mouth either, rather it would be worse. But you gotta breathe somehow, no?
And how would it even be possible to blow both nostrils at the same time in your (paper) handkerchief?
Well I guess it's possible but I just lack the imagination.