Happy Hypoxia? Unusual symptoms of a strange disease

Science article discusses a very unusual symptom of COVID-19 -- alarmingly low blood oxygen levels in people that seem to feel fine. Our lungs' main purpose is to provide oxygen to our blood, which carries the needed element to all of our organs and rest of our body. Usually, when someone has low blood oxygen levels, it is from major pneumonia etc. that keeps the lungs from inflating properly, and thus ventilators end up being needed to force the air through the lungs and into the blood.

With covid-19, some patients seem to look and feel fine, but have alarmingly low blood oxygen levels, without apparent inflammation of the lungs. In this case ventilators and other usual treatments may not be the right thing to do -- what is going on with these patients? This article mentions that it might be small blood clots in the lungs are responsible, blocking the oxygen flow into the blood. The coagulation (clotting) problem is well documented in COVID-19 patients, so maybe this is one of the key mechanisms of its damage. Maybe early monitoring of blood oxygen levels can be an effective strategy for management of mild symptoms and determination of when someone should go to the hospital?