It is "terrifying" (may be bit of an exaggeration, I'd call it deeply worrying) because if people who are sick is not tested, and is afraid of staying at home due to job concern and/or not caring since the disease is mild, they'd be spreading it further.

The sickness is not very serious for the young and healthy, it is quite deadly or the elderly (21%+ for 80+ people https://www.worldometers.info/coronavirus/coronavirus-age-se... ) - speaking as someone who live and work with elderly and/or compromised people, the long asymptomatic period is worrying enough on its own, the thought that there are people who are showing symptom but are still walking around going to work / movies / etc is scary.