The worshipers of devatās follow the rules of the books describing their worship, just as the Vaiṣṇavas worship Viṣṇu according to what is stated in the books dedicated to Viṣṇu worship. So there may be nothing wrong with the worship, but the destination of different worshipers is different. The worshipers of devas go to the devas, the worshipers of the Pitṛs go to the Pitṛs, the worshippers of ghosts go to the ghosts, and the worshipers of Kṛṣṇa live with Him.
The worshipers of devatās follow the rules of the books describing their worship, just as the Vaiṣṇavas worship Viṣṇu according to what is stated in the books dedicated to Viṣṇu worship. So there may be nothing wrong with the worship, but the destination of different worshipers is different. The worshipers of devas go to the devas, the worshipers of the Pitṛs go to the Pitṛs, the worshippers of ghosts go to the ghosts, and the worshipers of Kṛṣṇa live with Him. Those who worship Indra and others by ceremonies on the new and full moon days, being in the mode of goodness, go to those devas. Those in the mode of passion, who worship Pitṛs by śrāddha and other rituals, go to the Pitṛs. The worshipers of demons, in the mode of ignorance, who worship Yakṣas, Rākṣasas and others go to those demons. But only those who worship Kṛṣṇa, those who are beyond the modes of nature, who offer Him easily obtainable items go to Him. Though Kṛṣṇa is in the forms of the devatās, because the worshipers do not know this, they get a different result and do not attain Kṛṣṇa. And because the devas are destructible, their worshipers are destructible too. But the devotees are eternal and are not destroyed even at the time of pralaya. They experience great happiness close to Kṛṣṇa and play in His divine abode.