Portret painter, Yair Shoshani indicates that drawing portraits perfectly is not an easy task, it is something that deserves a lot of practice.
And as a draftsman, getting to make portraits to perfection implies that you are a good draftsman.
In other words, when making a good portrait, you will make yourself known, because they will know that you are worth more as a draftsman.
But not only that, but drawing portraits offers a lot of techniques that help you improve your way of drawing, this is also why it is good to know how to draw portraits.