Counterpoint:
Originally, viruses were classified as viruses because, although they are living "microbes" they are much smaller than bacteria.
Therefore they were not classified as bacteria.
However, some microbes and parasites do cause a thing we used to call infection/disease.
An infection can be labeled as toxicity in the cells. Indeed, a microbiologist can see a foreign entity which has invaded a human cell and can also see microbes outside of cells.
So, Maybe . . . .
Toxicity in the cells is an infection of a microbe which could reasonably be called a "disease"
Perhaps this proposal of "NO VIRUS EVER EXISTED" is a smidgeon too broad and it may even assume too many false connections?