The first words at that link are 'For most people, Covid-19 is a brief and mild disease'. Where does that information come from?

From what I've seen, COVID-19 is a systemic ailment and we're only beginning to understand all its effects. The only serious case in my personal sphere was a long time family friend who came out of the hospital thinking he'd recovered -- then he had a heart attack a week later and died.
Even this article is about how people are often apparently sicker than we thought. We should assume 'Long Covid' until we have evidential confirmation that it's not the norm.