Question: I came across the concept that although the Buddha is fully enlightened and has inconceivable powers, he cannot eradicate or change sentient beings’ karmic retribution. But if this is true, why do Buddhists practise reverencing him through body, speech and mind, via practices such as prostration before his image, making of offerings at shrines, chanting of sutras taught by him and mindfulness of his name?
Answer: What meant is the the Buddha cannot just alter anyone’s karma entirely by themselves. If he could, he would have done it long ago and we would all not have a single trace of suffering. However, anyone can learn and practise the above personally, as taught by him, so as to create positive karma. There can also be connection to him to receive his blessings, so as to transform one’s own negative karma by diluting its effects. The complete way to transcend all karmic suffering is to learn, practise and realise the Dharma that the Buddha realised.
To further understand how the Buddhas, although not omnipotent, are still, by default, the most powerful beings who can assist us in everyday lives, and to guide us towards Buddhahood, please see this article at https://thedailyenlightenment.com/2013/11/are-buddhas-omnipotent-omnibenevolent-omniscient