We must remember that we are limited,nature is not obligated to us to reveal its working to us and we know logic is not well defined to cover all our experiences and above all Life is not logical
It is yet another pointer to Sanatana Dharma being present in the south much earlier to Vedic period. The philosophical explanation of Yagnya follows in another article. I have noticed that the name Yagnyanarayanan is present in South India , among Brahmins. As this Avatar preceded Matsya, which took place after Manu had a family,Yagneswara is the first Avatar of Vishnu.