Why are viruses not considered living organisms, although they can multiply?

A virus is not a living organism because it cannot exist alone. Viruses always need other living things to live and reproduce. Once in the body, the virus attaches itself to receptors on the cell wall. This helps him get inside the cell. Then the virus is incorporated into the genotype of the cell, into its DNA. So he forces the cell to produce new viral particles. Such a cell can no longer perform its former work. Often, it is impossible to cure it, and after the death of the virus, the cell will also quickly die.