Unlike parasites, which try to live in symbiosis with the owner, or at least cause minimal harm to him. For example, tapeworms, bovine or pork tapeworm, these individuals live in the host's body in the amount of one individual, and if another tapeworm enters the body and begins to develop, the other will kill it, because the host may not withstand the toxic effects of two parasites.
The virus does not have such "brakes" and it develops rapidly and without stopping and in the final result kills itself or the host, it already depends on the pathogenicity of the virus.
It has no such function. Its function is the same as that of all organisms. Live and multiply. This is inherent in his genetic material. So ...
They can't prove otherwise, can they?