Can still have a void support. "In places where the mystical barriers between Runeterra and the Void have been worn thin, the air feels charged, and fantastical occurrences are the norm. Rivers run with vibrant colors, flowers bloom with incredible perfumes, and living beings experience psychedelic visions and surges in magical power. For a time, such places are wondrous and brimming with miracles, but soon the landscape is twisted into new and deadly forms, and if the Void is able to consume enough biomass to survive, it can grow and evolve into something ferocious and terrifying. " Some lore.
also a note, Debuffs can be supports kits, So a Parasite would realistically be more useful attacking enemy units then being a living armor for teammates. And in that regard a debuff void parasite is still very much viable and the only loss is the living armor fantasy which ultimately does not make for a great parasite.