[usrusr]

It's a virus that is completely unadapted to the human body, fresh off the boat from whatever animal it evolved on. It's like an early prototype medication: it already has the desired effect (reproduction in a body part that serves as a launch pad for transmission to other hosts), but it's chock-full off side effects. Unfortunately, it is so good at pre-symptomatic transmission that those side effects impose very little selection pressure.

At this point we have an interesting link to the topic of contact tracing apps: if we shift our countermeasures from wholesale isolation to fast, computerized contact tracing that is fast enough to overtake the infectivity/symptom last, it will increase the evolutionary advantage of less damaging strains (asymptomatic cases don't trigger a contacts cascade)

[raverbashing]

If you compare it to MERS/SARS it is actually less harmful (at an individual level) than those. But of course this ends up meaning more harmful at a collective level since it takes a while for people to develop symptoms while still being able to infect other people.