[T]he Chinese character for “great,” not that for “wonderful,” was put on each title of such sūtras as the Great Flower Garland Sūtra, the Sūtra of Great Assembly, the Great Wisdom Sūtra and the Great Nirvana Sūtra. These sūtras can save only people who are still alive but not dead ones, while the Lotus Sūtra can save dead people as well, which is why the sūtra is called “wonderful.” Therefore, those who are entitled to attain Buddhahood cannot do so by various other sūtras, while even those who have difficulty in attaining Buddhahood can become Buddhas by the Lotus Sūtra, let alone those who are easily capable of doing so. Accordingly, no one should rely on various other sūtras after the Lotus Sūtra was expounded.
Hokke Daimoku Shō, Treatise on the Daimoku of the Lotus Sūtra