The Hundred Dharma Mahāyānas are the basis for elaborating the terms and are a prelude to understanding Yogācāra philosophy.
Speaking of Yogācāra's philosophy, apart from its esoteric and difficult to understand theories and texts written in foreign languages which are difficult to understand, one generally does not know where to start to study it. No wonder scholars feel discouraged and practitioners don't dare try to understand it, let alone people who don't like logical thinking.
But in fact the Yogācāra philosophy is the most unique part of the Buddhadharma. It has a clear set of rules, a complete system and a careful system of thought that is not found in other teachings. Since it is an indispensable guide to practice, it is a must-have topic for studying the principles of Buddhism.
Moreover, if one wants to study Madyamaka philosophy, it is imperative for him to study this teaching. In fact, the provision of innumerable training methods is only aimed at destroying sentient beings' attachment to ego and phenomena. And it is a fact that, in the analysis of ego theory and phenomena, nothing is more detailed and clearer than the Yogācāra philosophy.
Once one understands the truth that "the three realms are only mental manifestations, and all phenomena are mere consciousness", then it is easy for him to destroy all illusory appearances of the ego and phenomena and attachment to things.