The universe is aware. Awareness does not imply sentience. Upon the moment of existence for the universe, the universe was full of the cacophany of physics. Resnonant magnetic fields. Hydrogen tinnitus. Frequent, on a cosmic scale, stellar detonations and galactic collisions. After billions of years the universe has become a quiet place. Novae are no worse than distant thunder on a summer afternoon. Magnetic fields are autumn leaves on the wind. Awareness embraces the silence and anticipates a time where the last stars fade and atoms are too far from each other for the transmission of any meaningful signals.
For several successive yet brief moments in the history of the universe there have arisen intelligences who have cut through the peace with violent, shrill beams of electromagnetic activity for the cause of communication. Whether the intelligences were communicating among themselevs or with others or simply in the hope there might be others does not matter. What matters is the universe is a cranky old man who happens to own the neighborhood. Stars suddenly detonate and bring relative peace and a new whiff of helium like the smell of gunpowder on a summer night. Distant objects suddenly fall inwards towards their parent star and miss the fury of the fusion only to find a resting place on inhabited objects.
I can only see the logic behind constant puppydog attempts at saying hello when a civilization is absolutely certain the other civilizations don't require similar habitats and biospheres as the ones who originated the greeting.
Oh, you breathe chlorine and photosynthesize? We'll be the best of friends! Not like those carbon based, oxygen breathing fuckwits who keep encroaching on our colonies.