SB 5.20.17

parasya brahmaṇaḥ sākṣāj
 jāta-vedo ’si havyavāṭ
devānāṁ puruṣāṅgānāṁ
 yajñena puruṣaṁ yajeti
parasya — of the Supreme; brahmaṇaḥ — Brahman; sākṣāt — directly; jāta-vedaḥ — O fire-god; asi — you are; havyavāṭ — the carrier of Vedic offerings of grains and ghee; devānām — of all the demigods; puruṣa-aṅgānām — who are limbs of the Supreme Person; yajñena — by performing the ritualistic sacrifices; puruṣam — to the Supreme Person; yaja — please carry oblations; iti — thus.
[This is the mantra by which the inhabitants of Kuśadvīpa worship the fire-god.] O fire-god, you are a part of the Supreme Personality of Godhead, Hari, and you carry to Him all the offerings of sacrifices. Therefore we request you to offer to the Supreme Personality of Godhead the yajñic ingredients we are offering the demigods, for the Lord is the real enjoyer.

The demigods are servants who assist the Supreme Personality of Godhead. If one worships the demigods, the demigods, as servants of the Supreme, carry the sacrificial offerings to the Lord, like tax collectors collecting revenue from the citizens and bringing it to the government’s treasury. The demigods cannot accept the sacrificial offerings; they simply carry the offerings to the Supreme Personality of Godhead. As stated by Śrīla Viśvanātha Cakravartī Ṭhākura, yasya prasādād bhagavat-prasādaḥ: since the guru is a representative of the Supreme Personality of Godhead, he carries to the Lord whatever is offered to him. Similarly, all the demigods, as faithful servants of the Supreme Lord, hand over to the Supreme Lord whatever is offered to them in sacrificial performances. There is no fault in worshiping the demigods with this understanding, but to think that the demigods are independent of the Supreme Personality of Godhead and equal to Him is called hṛta-jñāna, a loss of intelligence (kāmais tais tair hṛta jñānāḥ). One who thinks that the demigods themselves are the actual benefactors is mistaken.