The Brahmanas are the gods of the very gods. Whatever they would say would be for your great good. Therefore all kinds of sacrifices naturally belong to all the four orders. The celebration of these sacrifices is obligatory and not optional.
देवानामपि ये देवा यद् ब्रूयस्ते परं हितम्। तस्माद् वर्णैः सर्वयज्ञाः संसृज्यन्ते न काम्यया॥