I mean it even says that it's not the case that longer lines are necessarily better, just that you won't NEED to use a ton of shorter lines as you gain more skill and experience
But the way she present the idea left space to that childish responses. People were arguing that the style they are using classifies them as beginners dispute the experience they have. Not that beginner is a bad term, but the classification that everyone that does not use single lines are not pros.