I'm not sure it's entirely correct to refer to this instance by the term of "anthropic reasoning" too, but: The viruses we see are common because they reproduc

I'm not sure it's entirely correct to refer to this instance by the term of "anthropic reasoning" too, but: The viruses we see are common because they reproduce, it's not that they reproduce because they have some drive to become common. Thus prions are less common because they aren't as successful in spreading (for some reason(s) I don't know either).