I don't believe it is quite that mild so I suspect an out of context or misunderstood quote.
CV19 has a long incubation period, too. So, while people are just carriers, it's spreading exponentially. Then, on top of that, it is non-symptomatic or only mildly symptomatic for a whole lot of people, especially if they're healthy and young... the type that are actively engaged with many other people.
We, in the U.S., due to the lack of tests, only 'see' CV19 when someone (usually an at-risk person) gets seriously ill. And that one person is just the tip of the iceberg for those who are sick, but not seriously and only suspect they have CV19; for those who are sick mildly who think they just have a cold; for those who show no symptoms; and, for those still incubating it.