Why in new total thyrodectomy ligate sup pole not infirior pole?

Why in new total thyrodectomy ligate sup pole not infirior pole ???

The branches of both superior and inferior vascular pedicles are individually divided flush with the thyroid gland to avoid devascularizing the parathyroid glands (in case of the inferior artery) and to avoid injuring the external branch of the superior laryngeal nerve if the latter could not be clearly identified and protected in case of the superior thyroid artery.

Of course we don’t ligate main inf.thyroid artery to preserve vascularity of parathyroids, also,we work on terminal branches at level of thyroid capsule either with bipolar diathermy or harmonic scalpel in extra or subcapsular thyroidectomy.