They're basically a technicality and that's just because they don't have their own actual DNA and require hijacking cellular machinery in order to reproduce, is my understanding. Generally speaking viruses are kind of in that twilight zone just at the outer edge of what we could call "life" and functionally are a bit more like some kind of limited grey goo, resembling a bit more an organic biological machine than "life" in the strictly conventional sense. But of course with the discovery of prions I would indeed say that Brit was spot on in that the whole borderlines of what genuinely constitutes discrete "life" is much more hazy than we Westerners like to believe.
Speaking of which, it really actually is a much more cultural bias, in that Western thought tends to like truncating and categorizing everything. It reminds me of this Dave Chappelle skit https://www.youtube.com/watch?v=1NZJjUU4CyY
we really do unintentionally do this and it biases our complete worldview in semi-autism. Some other cultures like far Easterners and Native Americans tend towards a more holistic view, where to a European we see "there is the mountain, and the peaks, and the various tree lines, and the ice, and the river, and the streams, and the ocean" and so on, whereas these cultures tend to just see the interlinking things of the entire water cycle; the trees absorb the rains and respirate and the evaporated water falls as snow which melts which feeds streams and so on. It is also a difference in terms of typical linear thinking, which I suspect I'm processing differently in some non-linear way compared to lots of other people. Not saying there is any inherent "better" or inferiority/superiority to thought in fact that very premise is kind of what I mean about a Eurocentric thinking and perceiving style which is built on comparison and categorization, rather than interconnection and interelatedness which sees the forest for the trees and how each individual part makes up a piece of the whole dynamic system.
For instance, we as organisms are absolutely filled with non-human DNA that we need to function such as gut flora. Certain organisms are entirely dependent upon it for survival like termites, whose gut flora is what breaks down wood. I heard some theory that parts of evolution including our "junk" DNA may actually be the result of viruses interfering in our cellular and genetic machinery. In fact last I heard the one theory about photosynthesis was that somehow some ancient organism absorbed another unicellular organism and assimilated it and that that's what chloroplasts are https://en.wikipedia.org/wiki/Chloroplast#Primary_endosymbiosis
This is another huge problem I have with Western particularly Germanic thinking, which perceives things in an idiotic "nature is red in tooth and claw survival of the fittest means survival of the strongest!" thing, which completely and utterly ignores symbionts at both the cellular, species-group, and interspecies level for survival which has arguably played the overwhelming role in life on earth, the ramifications of which would probably transfer politically if you actually thought about them (for instance favoring something more like mutualism or a form of libertarianism than monarchism or dictatorship).
I would even further posit that if life had any inherent meaning, it is to evolve and spread more life, even if at the most basic thing that means us as a species effectively being a type of planetary infection that can and must consciously slumber its way to mutating new means of transmission so as to become spaceborne and thus infecting the other fomite planetary bodies of distant stars. We can possibly achieve this even by ejecting our material in their general direction and hoping whatever organisms can survive the cold vacuum and radiation of deep space until infecting another body with ourselves.